Merge branch 'master' into required_flags

.flake8

@@ -0,0 +1,2 @@
+[flake8]
+max-line-length = 120

.gitignore

@@ -0,0 +1,2 @@
+*.coverprofile
+node_modules/

.travis.yml

@@ -1,6 +1,27 @@
 language: go
-go: 1.1
+sudo: false
+dist: trusty
+osx_image: xcode8.3
+go: 1.11.x
+
+os:
+- linux
+- osx
+
+cache:
+  directories:
+  - node_modules
+
+before_script:
+- go get github.com/urfave/gfmrun/... || true
+- go get golang.org/x/tools/cmd/goimports
+- if [ ! -f node_modules/.bin/markdown-toc ] ; then
+    npm install markdown-toc ;
+  fi
 
 script:
-- go vet ./...
+- ./runtests gen
-- go test -v ./...
+- ./runtests vet
+- ./runtests test
+- ./runtests gfmrun
+- ./runtests toc

CHANGELOG.md

@@ -0,0 +1,435 @@
+# Change Log
+
+**ATTN**: This project uses [semantic versioning](http://semver.org/).
+
+## [Unreleased]
+
+## 1.20.0 - 2017-08-10
+
+### Fixed
+
+* `HandleExitCoder` is now correctly iterates over all errors in
+  a `MultiError`. The exit code is the exit code of the last error or `1` if
+  there are no `ExitCoder`s in the `MultiError`.
+* Fixed YAML file loading on Windows (previously would fail validate the file path)
+* Subcommand `Usage`, `Description`, `ArgsUsage`, `OnUsageError` correctly
+  propogated
+* `ErrWriter` is now passed downwards through command structure to avoid the
+  need to redefine it
+* Pass `Command` context into `OnUsageError` rather than parent context so that
+  all fields are avaiable
+* Errors occuring in `Before` funcs are no longer double printed
+* Use `UsageText` in the help templates for commands and subcommands if
+  defined; otherwise build the usage as before (was previously ignoring this
+  field)
+* `IsSet` and `GlobalIsSet` now correctly return whether a flag is set if
+  a program calls `Set` or `GlobalSet` directly after flag parsing (would
+  previously only return `true` if the flag was set during parsing)
+
+### Changed
+
+* No longer exit the program on command/subcommand error if the error raised is
+  not an `OsExiter`. This exiting behavior was introduced in 1.19.0, but was
+  determined to be a regression in functionality. See [the
+  PR](https://github.com/urfave/cli/pull/595) for discussion.
+
+### Added
+
+* `CommandsByName` type was added to make it easy to sort `Command`s by name,
+  alphabetically
+* `altsrc` now handles loading of string and int arrays from TOML
+* Support for definition of custom help templates for `App` via
+  `CustomAppHelpTemplate`
+* Support for arbitrary key/value fields on `App` to be used with
+  `CustomAppHelpTemplate` via `ExtraInfo`
+* `HelpFlag`, `VersionFlag`, and `BashCompletionFlag` changed to explictly be
+  `cli.Flag`s allowing for the use of custom flags satisfying the `cli.Flag`
+  interface to be used.
+
+
+## [1.19.1] - 2016-11-21
+
+### Fixed
+
+- Fixes regression introduced in 1.19.0 where using an `ActionFunc` as
+  the `Action` for a command would cause it to error rather than calling the
+  function. Should not have a affected declarative cases using `func(c
+  *cli.Context) err)`.
+- Shell completion now handles the case where the user specifies
+  `--generate-bash-completion` immediately after a flag that takes an argument.
+  Previously it call the application with `--generate-bash-completion` as the
+  flag value.
+
+## [1.19.0] - 2016-11-19
+### Added
+- `FlagsByName` was added to make it easy to sort flags (e.g. `sort.Sort(cli.FlagsByName(app.Flags))`)
+- A `Description` field was added to `App` for a more detailed description of
+  the application (similar to the existing `Description` field on `Command`)
+- Flag type code generation via `go generate`
+- Write to stderr and exit 1 if action returns non-nil error
+- Added support for TOML to the `altsrc` loader
+- `SkipArgReorder` was added to allow users to skip the argument reordering.
+  This is useful if you want to consider all "flags" after an argument as
+  arguments rather than flags (the default behavior of the stdlib `flag`
+  library). This is backported functionality from the [removal of the flag
+  reordering](https://github.com/urfave/cli/pull/398) in the unreleased version
+  2
+- For formatted errors (those implementing `ErrorFormatter`), the errors will
+  be formatted during output. Compatible with `pkg/errors`.
+
+### Changed
+- Raise minimum tested/supported Go version to 1.2+
+
+### Fixed
+- Consider empty environment variables as set (previously environment variables
+  with the equivalent of `""` would be skipped rather than their value used).
+- Return an error if the value in a given environment variable cannot be parsed
+  as the flag type. Previously these errors were silently swallowed.
+- Print full error when an invalid flag is specified (which includes the invalid flag)
+- `App.Writer` defaults to `stdout` when `nil`
+- If no action is specified on a command or app, the help is now printed instead of `panic`ing
+- `App.Metadata` is initialized automatically now (previously was `nil` unless initialized)
+- Correctly show help message if `-h` is provided to a subcommand
+- `context.(Global)IsSet` now respects environment variables. Previously it
+  would return `false` if a flag was specified in the environment rather than
+  as an argument
+- Removed deprecation warnings to STDERR to avoid them leaking to the end-user
+- `altsrc`s import paths were updated to use `gopkg.in/urfave/cli.v1`. This
+  fixes issues that occurred when `gopkg.in/urfave/cli.v1` was imported as well
+  as `altsrc` where Go would complain that the types didn't match
+
+## [1.18.1] - 2016-08-28
+### Fixed
+- Removed deprecation warnings to STDERR to avoid them leaking to the end-user (backported)
+
+## [1.18.0] - 2016-06-27
+### Added
+- `./runtests` test runner with coverage tracking by default
+- testing on OS X
+- testing on Windows
+- `UintFlag`, `Uint64Flag`, and `Int64Flag` types and supporting code
+
+### Changed
+- Use spaces for alignment in help/usage output instead of tabs, making the
+  output alignment consistent regardless of tab width
+
+### Fixed
+- Printing of command aliases in help text
+- Printing of visible flags for both struct and struct pointer flags
+- Display the `help` subcommand when using `CommandCategories`
+- No longer swallows `panic`s that occur within the `Action`s themselves when
+  detecting the signature of the `Action` field
+
+## [1.17.1] - 2016-08-28
+### Fixed
+- Removed deprecation warnings to STDERR to avoid them leaking to the end-user
+
+## [1.17.0] - 2016-05-09
+### Added
+- Pluggable flag-level help text rendering via `cli.DefaultFlagStringFunc`
+- `context.GlobalBoolT` was added as an analogue to `context.GlobalBool`
+- Support for hiding commands by setting `Hidden: true` -- this will hide the
+  commands in help output
+
+### Changed
+- `Float64Flag`, `IntFlag`, and `DurationFlag` default values are no longer
+  quoted in help text output.
+- All flag types now include `(default: {value})` strings following usage when a
+  default value can be (reasonably) detected.
+- `IntSliceFlag` and `StringSliceFlag` usage strings are now more consistent
+  with non-slice flag types
+- Apps now exit with a code of 3 if an unknown subcommand is specified
+  (previously they printed "No help topic for...", but still exited 0. This
+  makes it easier to script around apps built using `cli` since they can trust
+  that a 0 exit code indicated a successful execution.
+- cleanups based on [Go Report Card
+  feedback](https://goreportcard.com/report/github.com/urfave/cli)
+
+## [1.16.1] - 2016-08-28
+### Fixed
+- Removed deprecation warnings to STDERR to avoid them leaking to the end-user
+
+## [1.16.0] - 2016-05-02
+### Added
+- `Hidden` field on all flag struct types to omit from generated help text
+
+### Changed
+- `BashCompletionFlag` (`--enable-bash-completion`) is now omitted from
+generated help text via the `Hidden` field
+
+### Fixed
+- handling of error values in `HandleAction` and `HandleExitCoder`
+
+## [1.15.0] - 2016-04-30
+### Added
+- This file!
+- Support for placeholders in flag usage strings
+- `App.Metadata` map for arbitrary data/state management
+- `Set` and `GlobalSet` methods on `*cli.Context` for altering values after
+parsing.
+- Support for nested lookup of dot-delimited keys in structures loaded from
+YAML.
+
+### Changed
+- The `App.Action` and `Command.Action` now prefer a return signature of
+`func(*cli.Context) error`, as defined by `cli.ActionFunc`.  If a non-nil
+`error` is returned, there may be two outcomes:
+    - If the error fulfills `cli.ExitCoder`, then `os.Exit` will be called
+    automatically
+    - Else the error is bubbled up and returned from `App.Run`
+- Specifying an `Action` with the legacy return signature of
+`func(*cli.Context)` will produce a deprecation message to stderr
+- Specifying an `Action` that is not a `func` type will produce a non-zero exit
+from `App.Run`
+- Specifying an `Action` func that has an invalid (input) signature will
+produce a non-zero exit from `App.Run`
+
+### Deprecated
+- <a name="deprecated-cli-app-runandexitonerror"></a>
+`cli.App.RunAndExitOnError`, which should now be done by returning an error
+that fulfills `cli.ExitCoder` to `cli.App.Run`.
+- <a name="deprecated-cli-app-action-signature"></a> the legacy signature for
+`cli.App.Action` of `func(*cli.Context)`, which should now have a return
+signature of `func(*cli.Context) error`, as defined by `cli.ActionFunc`.
+
+### Fixed
+- Added missing `*cli.Context.GlobalFloat64` method
+
+## [1.14.0] - 2016-04-03 (backfilled 2016-04-25)
+### Added
+- Codebeat badge
+- Support for categorization via `CategorizedHelp` and `Categories` on app.
+
+### Changed
+- Use `filepath.Base` instead of `path.Base` in `Name` and `HelpName`.
+
+### Fixed
+- Ensure version is not shown in help text when `HideVersion` set.
+
+## [1.13.0] - 2016-03-06 (backfilled 2016-04-25)
+### Added
+- YAML file input support.
+- `NArg` method on context.
+
+## [1.12.0] - 2016-02-17 (backfilled 2016-04-25)
+### Added
+- Custom usage error handling.
+- Custom text support in `USAGE` section of help output.
+- Improved help messages for empty strings.
+- AppVeyor CI configuration.
+
+### Changed
+- Removed `panic` from default help printer func.
+- De-duping and optimizations.
+
+### Fixed
+- Correctly handle `Before`/`After` at command level when no subcommands.
+- Case of literal `-` argument causing flag reordering.
+- Environment variable hints on Windows.
+- Docs updates.
+
+## [1.11.1] - 2015-12-21 (backfilled 2016-04-25)
+### Changed
+- Use `path.Base` in `Name` and `HelpName`
+- Export `GetName` on flag types.
+
+### Fixed
+- Flag parsing when skipping is enabled.
+- Test output cleanup.
+- Move completion check to account for empty input case.
+
+## [1.11.0] - 2015-11-15 (backfilled 2016-04-25)
+### Added
+- Destination scan support for flags.
+- Testing against `tip` in Travis CI config.
+
+### Changed
+- Go version in Travis CI config.
+
+### Fixed
+- Removed redundant tests.
+- Use correct example naming in tests.
+
+## [1.10.2] - 2015-10-29 (backfilled 2016-04-25)
+### Fixed
+- Remove unused var in bash completion.
+
+## [1.10.1] - 2015-10-21 (backfilled 2016-04-25)
+### Added
+- Coverage and reference logos in README.
+
+### Fixed
+- Use specified values in help and version parsing.
+- Only display app version and help message once.
+
+## [1.10.0] - 2015-10-06 (backfilled 2016-04-25)
+### Added
+- More tests for existing functionality.
+- `ArgsUsage` at app and command level for help text flexibility.
+
+### Fixed
+- Honor `HideHelp` and `HideVersion` in `App.Run`.
+- Remove juvenile word from README.
+
+## [1.9.0] - 2015-09-08 (backfilled 2016-04-25)
+### Added
+- `FullName` on command with accompanying help output update.
+- Set default `$PROG` in bash completion.
+
+### Changed
+- Docs formatting.
+
+### Fixed
+- Removed self-referential imports in tests.
+
+## [1.8.0] - 2015-06-30 (backfilled 2016-04-25)
+### Added
+- Support for `Copyright` at app level.
+- `Parent` func at context level to walk up context lineage.
+
+### Fixed
+- Global flag processing at top level.
+
+## [1.7.1] - 2015-06-11 (backfilled 2016-04-25)
+### Added
+- Aggregate errors from `Before`/`After` funcs.
+- Doc comments on flag structs.
+- Include non-global flags when checking version and help.
+- Travis CI config updates.
+
+### Fixed
+- Ensure slice type flags have non-nil values.
+- Collect global flags from the full command hierarchy.
+- Docs prose.
+
+## [1.7.0] - 2015-05-03 (backfilled 2016-04-25)
+### Changed
+- `HelpPrinter` signature includes output writer.
+
+### Fixed
+- Specify go 1.1+ in docs.
+- Set `Writer` when running command as app.
+
+## [1.6.0] - 2015-03-23 (backfilled 2016-04-25)
+### Added
+- Multiple author support.
+- `NumFlags` at context level.
+- `Aliases` at command level.
+
+### Deprecated
+- `ShortName` at command level.
+
+### Fixed
+- Subcommand help output.
+- Backward compatible support for deprecated `Author` and `Email` fields.
+- Docs regarding `Names`/`Aliases`.
+
+## [1.5.0] - 2015-02-20 (backfilled 2016-04-25)
+### Added
+- `After` hook func support at app and command level.
+
+### Fixed
+- Use parsed context when running command as subcommand.
+- Docs prose.
+
+## [1.4.1] - 2015-01-09 (backfilled 2016-04-25)
+### Added
+- Support for hiding `-h / --help` flags, but not `help` subcommand.
+- Stop flag parsing after `--`.
+
+### Fixed
+- Help text for generic flags to specify single value.
+- Use double quotes in output for defaults.
+- Use `ParseInt` instead of `ParseUint` for int environment var values.
+- Use `0` as base when parsing int environment var values.
+
+## [1.4.0] - 2014-12-12 (backfilled 2016-04-25)
+### Added
+- Support for environment variable lookup "cascade".
+- Support for `Stdout` on app for output redirection.
+
+### Fixed
+- Print command help instead of app help in `ShowCommandHelp`.
+
+## [1.3.1] - 2014-11-13 (backfilled 2016-04-25)
+### Added
+- Docs and example code updates.
+
+### Changed
+- Default `-v / --version` flag made optional.
+
+## [1.3.0] - 2014-08-10 (backfilled 2016-04-25)
+### Added
+- `FlagNames` at context level.
+- Exposed `VersionPrinter` var for more control over version output.
+- Zsh completion hook.
+- `AUTHOR` section in default app help template.
+- Contribution guidelines.
+- `DurationFlag` type.
+
+## [1.2.0] - 2014-08-02
+### Added
+- Support for environment variable defaults on flags plus tests.
+
+## [1.1.0] - 2014-07-15
+### Added
+- Bash completion.
+- Optional hiding of built-in help command.
+- Optional skipping of flag parsing at command level.
+- `Author`, `Email`, and `Compiled` metadata on app.
+- `Before` hook func support at app and command level.
+- `CommandNotFound` func support at app level.
+- Command reference available on context.
+- `GenericFlag` type.
+- `Float64Flag` type.
+- `BoolTFlag` type.
+- `IsSet` flag helper on context.
+- More flag lookup funcs at context level.
+- More tests &amp; docs.
+
+### Changed
+- Help template updates to account for presence/absence of flags.
+- Separated subcommand help template.
+- Exposed `HelpPrinter` var for more control over help output.
+
+## [1.0.0] - 2013-11-01
+### Added
+- `help` flag in default app flag set and each command flag set.
+- Custom handling of argument parsing errors.
+- Command lookup by name at app level.
+- `StringSliceFlag` type and supporting `StringSlice` type.
+- `IntSliceFlag` type and supporting `IntSlice` type.
+- Slice type flag lookups by name at context level.
+- Export of app and command help functions.
+- More tests &amp; docs.
+
+## 0.1.0 - 2013-07-22
+### Added
+- Initial implementation.
+
+[Unreleased]: https://github.com/urfave/cli/compare/v1.18.0...HEAD
+[1.18.0]: https://github.com/urfave/cli/compare/v1.17.0...v1.18.0
+[1.17.0]: https://github.com/urfave/cli/compare/v1.16.0...v1.17.0
+[1.16.0]: https://github.com/urfave/cli/compare/v1.15.0...v1.16.0
+[1.15.0]: https://github.com/urfave/cli/compare/v1.14.0...v1.15.0
+[1.14.0]: https://github.com/urfave/cli/compare/v1.13.0...v1.14.0
+[1.13.0]: https://github.com/urfave/cli/compare/v1.12.0...v1.13.0
+[1.12.0]: https://github.com/urfave/cli/compare/v1.11.1...v1.12.0
+[1.11.1]: https://github.com/urfave/cli/compare/v1.11.0...v1.11.1
+[1.11.0]: https://github.com/urfave/cli/compare/v1.10.2...v1.11.0
+[1.10.2]: https://github.com/urfave/cli/compare/v1.10.1...v1.10.2
+[1.10.1]: https://github.com/urfave/cli/compare/v1.10.0...v1.10.1
+[1.10.0]: https://github.com/urfave/cli/compare/v1.9.0...v1.10.0
+[1.9.0]: https://github.com/urfave/cli/compare/v1.8.0...v1.9.0
+[1.8.0]: https://github.com/urfave/cli/compare/v1.7.1...v1.8.0
+[1.7.1]: https://github.com/urfave/cli/compare/v1.7.0...v1.7.1
+[1.7.0]: https://github.com/urfave/cli/compare/v1.6.0...v1.7.0
+[1.6.0]: https://github.com/urfave/cli/compare/v1.5.0...v1.6.0
+[1.5.0]: https://github.com/urfave/cli/compare/v1.4.1...v1.5.0
+[1.4.1]: https://github.com/urfave/cli/compare/v1.4.0...v1.4.1
+[1.4.0]: https://github.com/urfave/cli/compare/v1.3.1...v1.4.0
+[1.3.1]: https://github.com/urfave/cli/compare/v1.3.0...v1.3.1
+[1.3.0]: https://github.com/urfave/cli/compare/v1.2.0...v1.3.0
+[1.2.0]: https://github.com/urfave/cli/compare/v1.1.0...v1.2.0
+[1.1.0]: https://github.com/urfave/cli/compare/v1.0.0...v1.1.0
+[1.0.0]: https://github.com/urfave/cli/compare/v0.1.0...v1.0.0

CODE_OF_CONDUCT.md

@@ -0,0 +1,74 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, gender identity and expression, level of experience,
+education, socio-economic status, nationality, personal appearance, race,
+religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting Dan Buch at dan@meatballhat.com. All complaints will be
+reviewed and investigated and will result in a response that is deemed necessary
+and appropriate to the circumstances. The project team is obligated to maintain
+confidentiality with regard to the reporter of an incident.  Further details of
+specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
+

CONTRIBUTING.md

@@ -0,0 +1,19 @@
+## Contributing
+
+**NOTE**: the primary maintainer(s) may be found in
+[./MAINTAINERS.md](./MAINTAINERS.md).
+
+Feel free to put up a pull request to fix a bug or maybe add a feature. I will
+give it a code review and make sure that it does not break backwards
+compatibility. If I or any other collaborators agree that it is in line with
+the vision of the project, we will work with you to get the code into
+a mergeable state and merge it into the master branch.
+
+If you have contributed something significant to the project, we will most
+likely add you as a collaborator. As a collaborator you are given the ability
+to merge others pull requests. It is very important that new code does not
+break existing code, so be careful about what code you do choose to merge.
+
+If you feel like you have contributed to the project but have not yet been added
+as a collaborator, we probably forgot to add you :sweat_smile:.  Please open an
+issue!

LICENSE

@@ -1,21 +1,21 @@
-Copyright (C) 2013 Jeremy Saenz
+MIT License
-All Rights Reserved.
 
-MIT LICENSE
+Copyright (c) 2016 Jeremy Saenz & Contributors
 
-Permission is hereby granted, free of charge, to any person obtaining a copy of
+Permission is hereby granted, free of charge, to any person obtaining a copy
-this software and associated documentation files (the "Software"), to deal in
+of this software and associated documentation files (the "Software"), to deal
-the Software without restriction, including without limitation the rights to
+in the Software without restriction, including without limitation the rights
-use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-the Software, and to permit persons to whom the Software is furnished to do so,
+copies of the Software, and to permit persons to whom the Software is
-subject to the following conditions:
+furnished to do so, subject to the following conditions:
 
 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

MAINTAINERS.md

@@ -0,0 +1 @@
+- @meatballhat

altsrc/altsrc.go

@@ -0,0 +1,3 @@
+package altsrc
+
+//go:generate python ../generate-flag-types altsrc -i ../flag-types.json -o flag_generated.go

altsrc/flag.go

@@ -0,0 +1,261 @@
+package altsrc
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+// FlagInputSourceExtension is an extension interface of cli.Flag that
+// allows a value to be set on the existing parsed flags.
+type FlagInputSourceExtension interface {
+	cli.Flag
+	ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error
+}
+
+// ApplyInputSourceValues iterates over all provided flags and
+// executes ApplyInputSourceValue on flags implementing the
+// FlagInputSourceExtension interface to initialize these flags
+// to an alternate input source.
+func ApplyInputSourceValues(context *cli.Context, inputSourceContext InputSourceContext, flags []cli.Flag) error {
+	for _, f := range flags {
+		inputSourceExtendedFlag, isType := f.(FlagInputSourceExtension)
+		if isType {
+			err := inputSourceExtendedFlag.ApplyInputSourceValue(context, inputSourceContext)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// InitInputSource is used to to setup an InputSourceContext on a cli.Command Before method. It will create a new
+// input source based on the func provided. If there is no error it will then apply the new input source to any flags
+// that are supported by the input source
+func InitInputSource(flags []cli.Flag, createInputSource func() (InputSourceContext, error)) cli.BeforeFunc {
+	return func(context *cli.Context) error {
+		inputSource, err := createInputSource()
+		if err != nil {
+			return fmt.Errorf("Unable to create input source: inner error: \n'%v'", err.Error())
+		}
+
+		return ApplyInputSourceValues(context, inputSource, flags)
+	}
+}
+
+// InitInputSourceWithContext is used to to setup an InputSourceContext on a cli.Command Before method. It will create a new
+// input source based on the func provided with potentially using existing cli.Context values to initialize itself. If there is
+// no error it will then apply the new input source to any flags that are supported by the input source
+func InitInputSourceWithContext(flags []cli.Flag, createInputSource func(context *cli.Context) (InputSourceContext, error)) cli.BeforeFunc {
+	return func(context *cli.Context) error {
+		inputSource, err := createInputSource(context)
+		if err != nil {
+			return fmt.Errorf("Unable to create input source with context: inner error: \n'%v'", err.Error())
+		}
+
+		return ApplyInputSourceValues(context, inputSource, flags)
+	}
+}
+
+// ApplyInputSourceValue applies a generic value to the flagSet if required
+func (f *GenericFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
+			value, err := isc.Generic(f.GenericFlag.Name)
+			if err != nil {
+				return err
+			}
+			if value != nil {
+				eachName(f.Name, func(name string) {
+					f.set.Set(f.Name, value.String())
+				})
+			}
+		}
+	}
+
+	return nil
+}
+
+// ApplyInputSourceValue applies a StringSlice value to the flagSet if required
+func (f *StringSliceFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
+			value, err := isc.StringSlice(f.StringSliceFlag.Name)
+			if err != nil {
+				return err
+			}
+			if value != nil {
+				var sliceValue cli.StringSlice = value
+				eachName(f.Name, func(name string) {
+					underlyingFlag := f.set.Lookup(f.Name)
+					if underlyingFlag != nil {
+						underlyingFlag.Value = &sliceValue
+					}
+				})
+			}
+		}
+	}
+	return nil
+}
+
+// ApplyInputSourceValue applies a IntSlice value if required
+func (f *IntSliceFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
+			value, err := isc.IntSlice(f.IntSliceFlag.Name)
+			if err != nil {
+				return err
+			}
+			if value != nil {
+				var sliceValue cli.IntSlice = value
+				eachName(f.Name, func(name string) {
+					underlyingFlag := f.set.Lookup(f.Name)
+					if underlyingFlag != nil {
+						underlyingFlag.Value = &sliceValue
+					}
+				})
+			}
+		}
+	}
+	return nil
+}
+
+// ApplyInputSourceValue applies a Bool value to the flagSet if required
+func (f *BoolFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
+			value, err := isc.Bool(f.BoolFlag.Name)
+			if err != nil {
+				return err
+			}
+			if value {
+				eachName(f.Name, func(name string) {
+					f.set.Set(f.Name, strconv.FormatBool(value))
+				})
+			}
+		}
+	}
+	return nil
+}
+
+// ApplyInputSourceValue applies a BoolT value to the flagSet if required
+func (f *BoolTFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !context.IsSet(f.Name) && !isEnvVarSet(f.EnvVar) {
+			value, err := isc.BoolT(f.BoolTFlag.Name)
+			if err != nil {
+				return err
+			}
+			if !value {
+				eachName(f.Name, func(name string) {
+					f.set.Set(f.Name, strconv.FormatBool(value))
+				})
+			}
+		}
+	}
+	return nil
+}
+
+// ApplyInputSourceValue applies a String value to the flagSet if required
+func (f *StringFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
+			value, err := isc.String(f.StringFlag.Name)
+			if err != nil {
+				return err
+			}
+			if value != "" {
+				eachName(f.Name, func(name string) {
+					f.set.Set(f.Name, value)
+				})
+			}
+		}
+	}
+	return nil
+}
+
+// ApplyInputSourceValue applies a int value to the flagSet if required
+func (f *IntFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
+			value, err := isc.Int(f.IntFlag.Name)
+			if err != nil {
+				return err
+			}
+			if value > 0 {
+				eachName(f.Name, func(name string) {
+					f.set.Set(f.Name, strconv.FormatInt(int64(value), 10))
+				})
+			}
+		}
+	}
+	return nil
+}
+
+// ApplyInputSourceValue applies a Duration value to the flagSet if required
+func (f *DurationFlag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
+			value, err := isc.Duration(f.DurationFlag.Name)
+			if err != nil {
+				return err
+			}
+			if value > 0 {
+				eachName(f.Name, func(name string) {
+					f.set.Set(f.Name, value.String())
+				})
+			}
+		}
+	}
+	return nil
+}
+
+// ApplyInputSourceValue applies a Float64 value to the flagSet if required
+func (f *Float64Flag) ApplyInputSourceValue(context *cli.Context, isc InputSourceContext) error {
+	if f.set != nil {
+		if !(context.IsSet(f.Name) || isEnvVarSet(f.EnvVar)) {
+			value, err := isc.Float64(f.Float64Flag.Name)
+			if err != nil {
+				return err
+			}
+			if value > 0 {
+				floatStr := float64ToString(value)
+				eachName(f.Name, func(name string) {
+					f.set.Set(f.Name, floatStr)
+				})
+			}
+		}
+	}
+	return nil
+}
+
+func isEnvVarSet(envVars string) bool {
+	for _, envVar := range strings.Split(envVars, ",") {
+		envVar = strings.TrimSpace(envVar)
+		if _, ok := syscall.Getenv(envVar); ok {
+			// TODO: Can't use this for bools as
+			// set means that it was true or false based on
+			// Bool flag type, should work for other types
+			return true
+		}
+	}
+
+	return false
+}
+
+func float64ToString(f float64) string {
+	return fmt.Sprintf("%v", f)
+}
+
+func eachName(longName string, fn func(string)) {
+	parts := strings.Split(longName, ",")
+	for _, name := range parts {
+		name = strings.Trim(name, " ")
+		fn(name)
+	}
+}

altsrc/flag_generated.go

@@ -0,0 +1,347 @@
+package altsrc
+
+import (
+	"flag"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+// WARNING: This file is generated!
+
+// BoolFlag is the flag type that wraps cli.BoolFlag to allow
+// for other values to be specified
+type BoolFlag struct {
+	cli.BoolFlag
+	set *flag.FlagSet
+}
+
+// NewBoolFlag creates a new BoolFlag
+func NewBoolFlag(fl cli.BoolFlag) *BoolFlag {
+	return &BoolFlag{BoolFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped BoolFlag.Apply
+func (f *BoolFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.BoolFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped BoolFlag.ApplyWithError
+func (f *BoolFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.BoolFlag.ApplyWithError(set)
+}
+
+// BoolTFlag is the flag type that wraps cli.BoolTFlag to allow
+// for other values to be specified
+type BoolTFlag struct {
+	cli.BoolTFlag
+	set *flag.FlagSet
+}
+
+// NewBoolTFlag creates a new BoolTFlag
+func NewBoolTFlag(fl cli.BoolTFlag) *BoolTFlag {
+	return &BoolTFlag{BoolTFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped BoolTFlag.Apply
+func (f *BoolTFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.BoolTFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped BoolTFlag.ApplyWithError
+func (f *BoolTFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.BoolTFlag.ApplyWithError(set)
+}
+
+// DurationFlag is the flag type that wraps cli.DurationFlag to allow
+// for other values to be specified
+type DurationFlag struct {
+	cli.DurationFlag
+	set *flag.FlagSet
+}
+
+// NewDurationFlag creates a new DurationFlag
+func NewDurationFlag(fl cli.DurationFlag) *DurationFlag {
+	return &DurationFlag{DurationFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped DurationFlag.Apply
+func (f *DurationFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.DurationFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped DurationFlag.ApplyWithError
+func (f *DurationFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.DurationFlag.ApplyWithError(set)
+}
+
+// Float64Flag is the flag type that wraps cli.Float64Flag to allow
+// for other values to be specified
+type Float64Flag struct {
+	cli.Float64Flag
+	set *flag.FlagSet
+}
+
+// NewFloat64Flag creates a new Float64Flag
+func NewFloat64Flag(fl cli.Float64Flag) *Float64Flag {
+	return &Float64Flag{Float64Flag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped Float64Flag.Apply
+func (f *Float64Flag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.Float64Flag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped Float64Flag.ApplyWithError
+func (f *Float64Flag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.Float64Flag.ApplyWithError(set)
+}
+
+// GenericFlag is the flag type that wraps cli.GenericFlag to allow
+// for other values to be specified
+type GenericFlag struct {
+	cli.GenericFlag
+	set *flag.FlagSet
+}
+
+// NewGenericFlag creates a new GenericFlag
+func NewGenericFlag(fl cli.GenericFlag) *GenericFlag {
+	return &GenericFlag{GenericFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped GenericFlag.Apply
+func (f *GenericFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.GenericFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped GenericFlag.ApplyWithError
+func (f *GenericFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.GenericFlag.ApplyWithError(set)
+}
+
+// Int64Flag is the flag type that wraps cli.Int64Flag to allow
+// for other values to be specified
+type Int64Flag struct {
+	cli.Int64Flag
+	set *flag.FlagSet
+}
+
+// NewInt64Flag creates a new Int64Flag
+func NewInt64Flag(fl cli.Int64Flag) *Int64Flag {
+	return &Int64Flag{Int64Flag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped Int64Flag.Apply
+func (f *Int64Flag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.Int64Flag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped Int64Flag.ApplyWithError
+func (f *Int64Flag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.Int64Flag.ApplyWithError(set)
+}
+
+// IntFlag is the flag type that wraps cli.IntFlag to allow
+// for other values to be specified
+type IntFlag struct {
+	cli.IntFlag
+	set *flag.FlagSet
+}
+
+// NewIntFlag creates a new IntFlag
+func NewIntFlag(fl cli.IntFlag) *IntFlag {
+	return &IntFlag{IntFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped IntFlag.Apply
+func (f *IntFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.IntFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped IntFlag.ApplyWithError
+func (f *IntFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.IntFlag.ApplyWithError(set)
+}
+
+// IntSliceFlag is the flag type that wraps cli.IntSliceFlag to allow
+// for other values to be specified
+type IntSliceFlag struct {
+	cli.IntSliceFlag
+	set *flag.FlagSet
+}
+
+// NewIntSliceFlag creates a new IntSliceFlag
+func NewIntSliceFlag(fl cli.IntSliceFlag) *IntSliceFlag {
+	return &IntSliceFlag{IntSliceFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped IntSliceFlag.Apply
+func (f *IntSliceFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.IntSliceFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped IntSliceFlag.ApplyWithError
+func (f *IntSliceFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.IntSliceFlag.ApplyWithError(set)
+}
+
+// Int64SliceFlag is the flag type that wraps cli.Int64SliceFlag to allow
+// for other values to be specified
+type Int64SliceFlag struct {
+	cli.Int64SliceFlag
+	set *flag.FlagSet
+}
+
+// NewInt64SliceFlag creates a new Int64SliceFlag
+func NewInt64SliceFlag(fl cli.Int64SliceFlag) *Int64SliceFlag {
+	return &Int64SliceFlag{Int64SliceFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped Int64SliceFlag.Apply
+func (f *Int64SliceFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.Int64SliceFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped Int64SliceFlag.ApplyWithError
+func (f *Int64SliceFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.Int64SliceFlag.ApplyWithError(set)
+}
+
+// StringFlag is the flag type that wraps cli.StringFlag to allow
+// for other values to be specified
+type StringFlag struct {
+	cli.StringFlag
+	set *flag.FlagSet
+}
+
+// NewStringFlag creates a new StringFlag
+func NewStringFlag(fl cli.StringFlag) *StringFlag {
+	return &StringFlag{StringFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped StringFlag.Apply
+func (f *StringFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.StringFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped StringFlag.ApplyWithError
+func (f *StringFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.StringFlag.ApplyWithError(set)
+}
+
+// StringSliceFlag is the flag type that wraps cli.StringSliceFlag to allow
+// for other values to be specified
+type StringSliceFlag struct {
+	cli.StringSliceFlag
+	set *flag.FlagSet
+}
+
+// NewStringSliceFlag creates a new StringSliceFlag
+func NewStringSliceFlag(fl cli.StringSliceFlag) *StringSliceFlag {
+	return &StringSliceFlag{StringSliceFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped StringSliceFlag.Apply
+func (f *StringSliceFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.StringSliceFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped StringSliceFlag.ApplyWithError
+func (f *StringSliceFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.StringSliceFlag.ApplyWithError(set)
+}
+
+// Uint64Flag is the flag type that wraps cli.Uint64Flag to allow
+// for other values to be specified
+type Uint64Flag struct {
+	cli.Uint64Flag
+	set *flag.FlagSet
+}
+
+// NewUint64Flag creates a new Uint64Flag
+func NewUint64Flag(fl cli.Uint64Flag) *Uint64Flag {
+	return &Uint64Flag{Uint64Flag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped Uint64Flag.Apply
+func (f *Uint64Flag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.Uint64Flag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped Uint64Flag.ApplyWithError
+func (f *Uint64Flag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.Uint64Flag.ApplyWithError(set)
+}
+
+// UintFlag is the flag type that wraps cli.UintFlag to allow
+// for other values to be specified
+type UintFlag struct {
+	cli.UintFlag
+	set *flag.FlagSet
+}
+
+// NewUintFlag creates a new UintFlag
+func NewUintFlag(fl cli.UintFlag) *UintFlag {
+	return &UintFlag{UintFlag: fl, set: nil}
+}
+
+// Apply saves the flagSet for later usage calls, then calls the
+// wrapped UintFlag.Apply
+func (f *UintFlag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.UintFlag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls the
+// wrapped UintFlag.ApplyWithError
+func (f *UintFlag) ApplyWithError(set *flag.FlagSet) error {
+	f.set = set
+	return f.UintFlag.ApplyWithError(set)
+}

altsrc/flag_test.go

@@ -0,0 +1,336 @@
+package altsrc
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+type testApplyInputSource struct {
+	Flag               FlagInputSourceExtension
+	FlagName           string
+	FlagSetName        string
+	Expected           string
+	ContextValueString string
+	ContextValue       flag.Value
+	EnvVarValue        string
+	EnvVarName         string
+	MapValue           interface{}
+}
+
+func TestGenericApplyInputSourceValue(t *testing.T) {
+	v := &Parser{"abc", "def"}
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewGenericFlag(cli.GenericFlag{Name: "test", Value: &Parser{}}),
+		FlagName: "test",
+		MapValue: v,
+	})
+	expect(t, v, c.Generic("test"))
+}
+
+func TestGenericApplyInputSourceMethodContextSet(t *testing.T) {
+	p := &Parser{"abc", "def"}
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewGenericFlag(cli.GenericFlag{Name: "test", Value: &Parser{}}),
+		FlagName:           "test",
+		MapValue:           &Parser{"efg", "hig"},
+		ContextValueString: p.String(),
+	})
+	expect(t, p, c.Generic("test"))
+}
+
+func TestGenericApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewGenericFlag(cli.GenericFlag{Name: "test", Value: &Parser{}, EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    &Parser{"efg", "hij"},
+		EnvVarName:  "TEST",
+		EnvVarValue: "abc,def",
+	})
+	expect(t, &Parser{"abc", "def"}, c.Generic("test"))
+}
+
+func TestStringSliceApplyInputSourceValue(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewStringSliceFlag(cli.StringSliceFlag{Name: "test"}),
+		FlagName: "test",
+		MapValue: []interface{}{"hello", "world"},
+	})
+	expect(t, c.StringSlice("test"), []string{"hello", "world"})
+}
+
+func TestStringSliceApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewStringSliceFlag(cli.StringSliceFlag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           []interface{}{"hello", "world"},
+		ContextValueString: "ohno",
+	})
+	expect(t, c.StringSlice("test"), []string{"ohno"})
+}
+
+func TestStringSliceApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewStringSliceFlag(cli.StringSliceFlag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    []interface{}{"hello", "world"},
+		EnvVarName:  "TEST",
+		EnvVarValue: "oh,no",
+	})
+	expect(t, c.StringSlice("test"), []string{"oh", "no"})
+}
+
+func TestIntSliceApplyInputSourceValue(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewIntSliceFlag(cli.IntSliceFlag{Name: "test"}),
+		FlagName: "test",
+		MapValue: []interface{}{1, 2},
+	})
+	expect(t, c.IntSlice("test"), []int{1, 2})
+}
+
+func TestIntSliceApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewIntSliceFlag(cli.IntSliceFlag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           []interface{}{1, 2},
+		ContextValueString: "3",
+	})
+	expect(t, c.IntSlice("test"), []int{3})
+}
+
+func TestIntSliceApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewIntSliceFlag(cli.IntSliceFlag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    []interface{}{1, 2},
+		EnvVarName:  "TEST",
+		EnvVarValue: "3,4",
+	})
+	expect(t, c.IntSlice("test"), []int{3, 4})
+}
+
+func TestBoolApplyInputSourceMethodSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewBoolFlag(cli.BoolFlag{Name: "test"}),
+		FlagName: "test",
+		MapValue: true,
+	})
+	expect(t, true, c.Bool("test"))
+}
+
+func TestBoolApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewBoolFlag(cli.BoolFlag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           false,
+		ContextValueString: "true",
+	})
+	expect(t, true, c.Bool("test"))
+}
+
+func TestBoolApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewBoolFlag(cli.BoolFlag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    false,
+		EnvVarName:  "TEST",
+		EnvVarValue: "true",
+	})
+	expect(t, true, c.Bool("test"))
+}
+
+func TestBoolTApplyInputSourceMethodSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewBoolTFlag(cli.BoolTFlag{Name: "test"}),
+		FlagName: "test",
+		MapValue: false,
+	})
+	expect(t, false, c.BoolT("test"))
+}
+
+func TestBoolTApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewBoolTFlag(cli.BoolTFlag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           true,
+		ContextValueString: "false",
+	})
+	expect(t, false, c.BoolT("test"))
+}
+
+func TestBoolTApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewBoolTFlag(cli.BoolTFlag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    true,
+		EnvVarName:  "TEST",
+		EnvVarValue: "false",
+	})
+	expect(t, false, c.BoolT("test"))
+}
+
+func TestStringApplyInputSourceMethodSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewStringFlag(cli.StringFlag{Name: "test"}),
+		FlagName: "test",
+		MapValue: "hello",
+	})
+	expect(t, "hello", c.String("test"))
+}
+
+func TestStringApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewStringFlag(cli.StringFlag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           "hello",
+		ContextValueString: "goodbye",
+	})
+	expect(t, "goodbye", c.String("test"))
+}
+
+func TestStringApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewStringFlag(cli.StringFlag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    "hello",
+		EnvVarName:  "TEST",
+		EnvVarValue: "goodbye",
+	})
+	expect(t, "goodbye", c.String("test"))
+}
+
+func TestIntApplyInputSourceMethodSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewIntFlag(cli.IntFlag{Name: "test"}),
+		FlagName: "test",
+		MapValue: 15,
+	})
+	expect(t, 15, c.Int("test"))
+}
+
+func TestIntApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewIntFlag(cli.IntFlag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           15,
+		ContextValueString: "7",
+	})
+	expect(t, 7, c.Int("test"))
+}
+
+func TestIntApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewIntFlag(cli.IntFlag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    15,
+		EnvVarName:  "TEST",
+		EnvVarValue: "12",
+	})
+	expect(t, 12, c.Int("test"))
+}
+
+func TestDurationApplyInputSourceMethodSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewDurationFlag(cli.DurationFlag{Name: "test"}),
+		FlagName: "test",
+		MapValue: time.Duration(30 * time.Second),
+	})
+	expect(t, time.Duration(30*time.Second), c.Duration("test"))
+}
+
+func TestDurationApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewDurationFlag(cli.DurationFlag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           time.Duration(30 * time.Second),
+		ContextValueString: time.Duration(15 * time.Second).String(),
+	})
+	expect(t, time.Duration(15*time.Second), c.Duration("test"))
+}
+
+func TestDurationApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewDurationFlag(cli.DurationFlag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    time.Duration(30 * time.Second),
+		EnvVarName:  "TEST",
+		EnvVarValue: time.Duration(15 * time.Second).String(),
+	})
+	expect(t, time.Duration(15*time.Second), c.Duration("test"))
+}
+
+func TestFloat64ApplyInputSourceMethodSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:     NewFloat64Flag(cli.Float64Flag{Name: "test"}),
+		FlagName: "test",
+		MapValue: 1.3,
+	})
+	expect(t, 1.3, c.Float64("test"))
+}
+
+func TestFloat64ApplyInputSourceMethodContextSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:               NewFloat64Flag(cli.Float64Flag{Name: "test"}),
+		FlagName:           "test",
+		MapValue:           1.3,
+		ContextValueString: fmt.Sprintf("%v", 1.4),
+	})
+	expect(t, 1.4, c.Float64("test"))
+}
+
+func TestFloat64ApplyInputSourceMethodEnvVarSet(t *testing.T) {
+	c := runTest(t, testApplyInputSource{
+		Flag:        NewFloat64Flag(cli.Float64Flag{Name: "test", EnvVar: "TEST"}),
+		FlagName:    "test",
+		MapValue:    1.3,
+		EnvVarName:  "TEST",
+		EnvVarValue: fmt.Sprintf("%v", 1.4),
+	})
+	expect(t, 1.4, c.Float64("test"))
+}
+
+func runTest(t *testing.T, test testApplyInputSource) *cli.Context {
+	inputSource := &MapInputSource{valueMap: map[interface{}]interface{}{test.FlagName: test.MapValue}}
+	set := flag.NewFlagSet(test.FlagSetName, flag.ContinueOnError)
+	c := cli.NewContext(nil, set, nil)
+	if test.EnvVarName != "" && test.EnvVarValue != "" {
+		os.Setenv(test.EnvVarName, test.EnvVarValue)
+		defer os.Setenv(test.EnvVarName, "")
+	}
+
+	test.Flag.Apply(set)
+	if test.ContextValue != nil {
+		flag := set.Lookup(test.FlagName)
+		flag.Value = test.ContextValue
+	}
+	if test.ContextValueString != "" {
+		set.Set(test.FlagName, test.ContextValueString)
+	}
+	test.Flag.ApplyInputSourceValue(c, inputSource)
+
+	return c
+}
+
+type Parser [2]string
+
+func (p *Parser) Set(value string) error {
+	parts := strings.Split(value, ",")
+	if len(parts) != 2 {
+		return fmt.Errorf("invalid format")
+	}
+
+	(*p)[0] = parts[0]
+	(*p)[1] = parts[1]
+
+	return nil
+}
+
+func (p *Parser) String() string {
+	return fmt.Sprintf("%s,%s", p[0], p[1])
+}

altsrc/helpers_test.go

@@ -0,0 +1,18 @@
+package altsrc
+
+import (
+	"reflect"
+	"testing"
+)
+
+func expect(t *testing.T, a interface{}, b interface{}) {
+	if !reflect.DeepEqual(b, a) {
+		t.Errorf("Expected %#v (type %v) - Got %#v (type %v)", b, reflect.TypeOf(b), a, reflect.TypeOf(a))
+	}
+}
+
+func refute(t *testing.T, a interface{}, b interface{}) {
+	if a == b {
+		t.Errorf("Did not expect %v (type %v) - Got %v (type %v)", b, reflect.TypeOf(b), a, reflect.TypeOf(a))
+	}
+}

altsrc/input_source_context.go

@@ -0,0 +1,21 @@
+package altsrc
+
+import (
+	"time"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+// InputSourceContext is an interface used to allow
+// other input sources to be implemented as needed.
+type InputSourceContext interface {
+	Int(name string) (int, error)
+	Duration(name string) (time.Duration, error)
+	Float64(name string) (float64, error)
+	String(name string) (string, error)
+	StringSlice(name string) ([]string, error)
+	IntSlice(name string) ([]int, error)
+	Generic(name string) (cli.Generic, error)
+	Bool(name string) (bool, error)
+	BoolT(name string) (bool, error)
+}

altsrc/json_command_test.go

@@ -0,0 +1,324 @@
+package altsrc
+
+import (
+	"flag"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+const (
+	fileName   = "current.json"
+	simpleJSON = `{"test": 15}`
+	nestedJSON = `{"top": {"test": 15}}`
+)
+
+func TestCommandJSONFileTest(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, simpleJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	test := []string{"test-cmd", "--load", fileName}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test"}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileTestGlobalEnvVarWins(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, simpleJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	os.Setenv("THE_TEST", "10")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", fileName}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 10)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", EnvVar: "THE_TEST"}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileTestGlobalEnvVarWinsNested(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, nestedJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	os.Setenv("THE_TEST", "10")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", fileName}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 10)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", EnvVar: "THE_TEST"}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileTestSpecifiedFlagWins(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, simpleJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	test := []string{"test-cmd", "--load", fileName, "--test", "7"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 7)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test"}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileTestSpecifiedFlagWinsNested(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, nestedJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	test := []string{"test-cmd", "--load", fileName, "--top.test", "7"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 7)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test"}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileTestDefaultValueFileWins(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, simpleJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	test := []string{"test-cmd", "--load", fileName}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", Value: 7}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileTestDefaultValueFileWinsNested(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, nestedJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	test := []string{"test-cmd", "--load", fileName}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", Value: 7}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileFlagHasDefaultGlobalEnvJSONSetGlobalEnvWins(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, simpleJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	os.Setenv("THE_TEST", "11")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", fileName}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 11)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", Value: 7, EnvVar: "THE_TEST"}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandJSONFileFlagHasDefaultGlobalEnvJSONSetGlobalEnvWinsNested(t *testing.T) {
+	cleanup := writeTempFile(t, fileName, nestedJSON)
+	defer cleanup()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	os.Setenv("THE_TEST", "11")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", fileName}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 11)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", Value: 7, EnvVar: "THE_TEST"}),
+			&cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewJSONSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func writeTempFile(t *testing.T, name string, content string) func() {
+	if err := ioutil.WriteFile(name, []byte(content), 0666); err != nil {
+		t.Fatalf("cannot write %q: %v", name, err)
+	}
+	return func() {
+		if err := os.Remove(name); err != nil {
+			t.Errorf("cannot remove %q: %v", name, err)
+		}
+	}
+}

altsrc/json_source_context.go

@@ -0,0 +1,208 @@
+package altsrc
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"strings"
+	"time"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+// NewJSONSourceFromFlagFunc returns a func that takes a cli.Context
+// and returns an InputSourceContext suitable for retrieving config
+// variables from a file containing JSON data with the file name defined
+// by the given flag.
+func NewJSONSourceFromFlagFunc(flag string) func(c *cli.Context) (InputSourceContext, error) {
+	return func(context *cli.Context) (InputSourceContext, error) {
+		return NewJSONSourceFromFile(context.String(flag))
+	}
+}
+
+// NewJSONSourceFromFile returns an InputSourceContext suitable for
+// retrieving config variables from a file (or url) containing JSON
+// data.
+func NewJSONSourceFromFile(f string) (InputSourceContext, error) {
+	data, err := loadDataFrom(f)
+	if err != nil {
+		return nil, err
+	}
+	return NewJSONSource(data)
+}
+
+// NewJSONSourceFromReader returns an InputSourceContext suitable for
+// retrieving config variables from an io.Reader that returns JSON data.
+func NewJSONSourceFromReader(r io.Reader) (InputSourceContext, error) {
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+	return NewJSONSource(data)
+}
+
+// NewJSONSource returns an InputSourceContext suitable for retrieving
+// config variables from raw JSON data.
+func NewJSONSource(data []byte) (InputSourceContext, error) {
+	var deserialized map[string]interface{}
+	if err := json.Unmarshal(data, &deserialized); err != nil {
+		return nil, err
+	}
+	return &jsonSource{deserialized: deserialized}, nil
+}
+
+func (x *jsonSource) Int(name string) (int, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return 0, err
+	}
+	switch v := i.(type) {
+	default:
+		return 0, fmt.Errorf("unexpected type %T for %q", i, name)
+	case int:
+		return v, nil
+	case float64:
+		return int(float64(v)), nil
+	case float32:
+		return int(float32(v)), nil
+	}
+}
+
+func (x *jsonSource) Duration(name string) (time.Duration, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return 0, err
+	}
+	v, ok := (time.Duration)(0), false
+	if v, ok = i.(time.Duration); !ok {
+		return v, fmt.Errorf("unexpected type %T for %q", i, name)
+	}
+	return v, nil
+}
+
+func (x *jsonSource) Float64(name string) (float64, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return 0, err
+	}
+	v, ok := (float64)(0), false
+	if v, ok = i.(float64); !ok {
+		return v, fmt.Errorf("unexpected type %T for %q", i, name)
+	}
+	return v, nil
+}
+
+func (x *jsonSource) String(name string) (string, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return "", err
+	}
+	v, ok := "", false
+	if v, ok = i.(string); !ok {
+		return v, fmt.Errorf("unexpected type %T for %q", i, name)
+	}
+	return v, nil
+}
+
+func (x *jsonSource) StringSlice(name string) ([]string, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return nil, err
+	}
+	switch v := i.(type) {
+	default:
+		return nil, fmt.Errorf("unexpected type %T for %q", i, name)
+	case []string:
+		return v, nil
+	case []interface{}:
+		c := []string{}
+		for _, s := range v {
+			if str, ok := s.(string); ok {
+				c = append(c, str)
+			} else {
+				return c, fmt.Errorf("unexpected item type %T in %T for %q", s, c, name)
+			}
+		}
+		return c, nil
+	}
+}
+
+func (x *jsonSource) IntSlice(name string) ([]int, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return nil, err
+	}
+	switch v := i.(type) {
+	default:
+		return nil, fmt.Errorf("unexpected type %T for %q", i, name)
+	case []int:
+		return v, nil
+	case []interface{}:
+		c := []int{}
+		for _, s := range v {
+			if i2, ok := s.(int); ok {
+				c = append(c, i2)
+			} else {
+				return c, fmt.Errorf("unexpected item type %T in %T for %q", s, c, name)
+			}
+		}
+		return c, nil
+	}
+}
+
+func (x *jsonSource) Generic(name string) (cli.Generic, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return nil, err
+	}
+	v, ok := (cli.Generic)(nil), false
+	if v, ok = i.(cli.Generic); !ok {
+		return v, fmt.Errorf("unexpected type %T for %q", i, name)
+	}
+	return v, nil
+}
+
+func (x *jsonSource) Bool(name string) (bool, error) {
+	i, err := x.getValue(name)
+	if err != nil {
+		return false, err
+	}
+	v, ok := false, false
+	if v, ok = i.(bool); !ok {
+		return v, fmt.Errorf("unexpected type %T for %q", i, name)
+	}
+	return v, nil
+}
+
+// since this source appears to require all configuration to be specified, the
+// concept of a boolean defaulting to true seems inconsistent with no defaults
+func (x *jsonSource) BoolT(name string) (bool, error) {
+	return false, fmt.Errorf("unsupported type BoolT for JSONSource")
+}
+
+func (x *jsonSource) getValue(key string) (interface{}, error) {
+	return jsonGetValue(key, x.deserialized)
+}
+
+func jsonGetValue(key string, m map[string]interface{}) (interface{}, error) {
+	var ret interface{}
+	var ok bool
+	working := m
+	keys := strings.Split(key, ".")
+	for ix, k := range keys {
+		if ret, ok = working[k]; !ok {
+			return ret, fmt.Errorf("missing key %q", key)
+		}
+		if working, ok = ret.(map[string]interface{}); !ok {
+			if ix < len(keys)-1 {
+				return ret, fmt.Errorf("unexpected intermediate value at %q segment of %q: %T", k, key, ret)
+			}
+		}
+	}
+	return ret, nil
+}
+
+type jsonSource struct {
+	deserialized map[string]interface{}
+}

altsrc/map_input_source.go

@@ -0,0 +1,262 @@
+package altsrc
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+	"time"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+// MapInputSource implements InputSourceContext to return
+// data from the map that is loaded.
+type MapInputSource struct {
+	valueMap map[interface{}]interface{}
+}
+
+// nestedVal checks if the name has '.' delimiters.
+// If so, it tries to traverse the tree by the '.' delimited sections to find
+// a nested value for the key.
+func nestedVal(name string, tree map[interface{}]interface{}) (interface{}, bool) {
+	if sections := strings.Split(name, "."); len(sections) > 1 {
+		node := tree
+		for _, section := range sections[:len(sections)-1] {
+			child, ok := node[section]
+			if !ok {
+				return nil, false
+			}
+			ctype, ok := child.(map[interface{}]interface{})
+			if !ok {
+				return nil, false
+			}
+			node = ctype
+		}
+		if val, ok := node[sections[len(sections)-1]]; ok {
+			return val, true
+		}
+	}
+	return nil, false
+}
+
+// Int returns an int from the map if it exists otherwise returns 0
+func (fsm *MapInputSource) Int(name string) (int, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if exists {
+		otherValue, isType := otherGenericValue.(int)
+		if !isType {
+			return 0, incorrectTypeForFlagError(name, "int", otherGenericValue)
+		}
+		return otherValue, nil
+	}
+	nestedGenericValue, exists := nestedVal(name, fsm.valueMap)
+	if exists {
+		otherValue, isType := nestedGenericValue.(int)
+		if !isType {
+			return 0, incorrectTypeForFlagError(name, "int", nestedGenericValue)
+		}
+		return otherValue, nil
+	}
+
+	return 0, nil
+}
+
+// Duration returns a duration from the map if it exists otherwise returns 0
+func (fsm *MapInputSource) Duration(name string) (time.Duration, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if exists {
+		otherValue, isType := otherGenericValue.(time.Duration)
+		if !isType {
+			return 0, incorrectTypeForFlagError(name, "duration", otherGenericValue)
+		}
+		return otherValue, nil
+	}
+	nestedGenericValue, exists := nestedVal(name, fsm.valueMap)
+	if exists {
+		otherValue, isType := nestedGenericValue.(time.Duration)
+		if !isType {
+			return 0, incorrectTypeForFlagError(name, "duration", nestedGenericValue)
+		}
+		return otherValue, nil
+	}
+
+	return 0, nil
+}
+
+// Float64 returns an float64 from the map if it exists otherwise returns 0
+func (fsm *MapInputSource) Float64(name string) (float64, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if exists {
+		otherValue, isType := otherGenericValue.(float64)
+		if !isType {
+			return 0, incorrectTypeForFlagError(name, "float64", otherGenericValue)
+		}
+		return otherValue, nil
+	}
+	nestedGenericValue, exists := nestedVal(name, fsm.valueMap)
+	if exists {
+		otherValue, isType := nestedGenericValue.(float64)
+		if !isType {
+			return 0, incorrectTypeForFlagError(name, "float64", nestedGenericValue)
+		}
+		return otherValue, nil
+	}
+
+	return 0, nil
+}
+
+// String returns a string from the map if it exists otherwise returns an empty string
+func (fsm *MapInputSource) String(name string) (string, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if exists {
+		otherValue, isType := otherGenericValue.(string)
+		if !isType {
+			return "", incorrectTypeForFlagError(name, "string", otherGenericValue)
+		}
+		return otherValue, nil
+	}
+	nestedGenericValue, exists := nestedVal(name, fsm.valueMap)
+	if exists {
+		otherValue, isType := nestedGenericValue.(string)
+		if !isType {
+			return "", incorrectTypeForFlagError(name, "string", nestedGenericValue)
+		}
+		return otherValue, nil
+	}
+
+	return "", nil
+}
+
+// StringSlice returns an []string from the map if it exists otherwise returns nil
+func (fsm *MapInputSource) StringSlice(name string) ([]string, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if !exists {
+		otherGenericValue, exists = nestedVal(name, fsm.valueMap)
+		if !exists {
+			return nil, nil
+		}
+	}
+
+	otherValue, isType := otherGenericValue.([]interface{})
+	if !isType {
+		return nil, incorrectTypeForFlagError(name, "[]interface{}", otherGenericValue)
+	}
+
+	var stringSlice = make([]string, 0, len(otherValue))
+	for i, v := range otherValue {
+		stringValue, isType := v.(string)
+
+		if !isType {
+			return nil, incorrectTypeForFlagError(fmt.Sprintf("%s[%d]", name, i), "string", v)
+		}
+
+		stringSlice = append(stringSlice, stringValue)
+	}
+
+	return stringSlice, nil
+}
+
+// IntSlice returns an []int from the map if it exists otherwise returns nil
+func (fsm *MapInputSource) IntSlice(name string) ([]int, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if !exists {
+		otherGenericValue, exists = nestedVal(name, fsm.valueMap)
+		if !exists {
+			return nil, nil
+		}
+	}
+
+	otherValue, isType := otherGenericValue.([]interface{})
+	if !isType {
+		return nil, incorrectTypeForFlagError(name, "[]interface{}", otherGenericValue)
+	}
+
+	var intSlice = make([]int, 0, len(otherValue))
+	for i, v := range otherValue {
+		intValue, isType := v.(int)
+
+		if !isType {
+			return nil, incorrectTypeForFlagError(fmt.Sprintf("%s[%d]", name, i), "int", v)
+		}
+
+		intSlice = append(intSlice, intValue)
+	}
+
+	return intSlice, nil
+}
+
+// Generic returns an cli.Generic from the map if it exists otherwise returns nil
+func (fsm *MapInputSource) Generic(name string) (cli.Generic, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if exists {
+		otherValue, isType := otherGenericValue.(cli.Generic)
+		if !isType {
+			return nil, incorrectTypeForFlagError(name, "cli.Generic", otherGenericValue)
+		}
+		return otherValue, nil
+	}
+	nestedGenericValue, exists := nestedVal(name, fsm.valueMap)
+	if exists {
+		otherValue, isType := nestedGenericValue.(cli.Generic)
+		if !isType {
+			return nil, incorrectTypeForFlagError(name, "cli.Generic", nestedGenericValue)
+		}
+		return otherValue, nil
+	}
+
+	return nil, nil
+}
+
+// Bool returns an bool from the map otherwise returns false
+func (fsm *MapInputSource) Bool(name string) (bool, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if exists {
+		otherValue, isType := otherGenericValue.(bool)
+		if !isType {
+			return false, incorrectTypeForFlagError(name, "bool", otherGenericValue)
+		}
+		return otherValue, nil
+	}
+	nestedGenericValue, exists := nestedVal(name, fsm.valueMap)
+	if exists {
+		otherValue, isType := nestedGenericValue.(bool)
+		if !isType {
+			return false, incorrectTypeForFlagError(name, "bool", nestedGenericValue)
+		}
+		return otherValue, nil
+	}
+
+	return false, nil
+}
+
+// BoolT returns an bool from the map otherwise returns true
+func (fsm *MapInputSource) BoolT(name string) (bool, error) {
+	otherGenericValue, exists := fsm.valueMap[name]
+	if exists {
+		otherValue, isType := otherGenericValue.(bool)
+		if !isType {
+			return true, incorrectTypeForFlagError(name, "bool", otherGenericValue)
+		}
+		return otherValue, nil
+	}
+	nestedGenericValue, exists := nestedVal(name, fsm.valueMap)
+	if exists {
+		otherValue, isType := nestedGenericValue.(bool)
+		if !isType {
+			return true, incorrectTypeForFlagError(name, "bool", nestedGenericValue)
+		}
+		return otherValue, nil
+	}
+
+	return true, nil
+}
+
+func incorrectTypeForFlagError(name, expectedTypeName string, value interface{}) error {
+	valueType := reflect.TypeOf(value)
+	valueTypeName := ""
+	if valueType != nil {
+		valueTypeName = valueType.Name()
+	}
+
+	return fmt.Errorf("Mismatched type for flag '%s'. Expected '%s' but actual is '%s'", name, expectedTypeName, valueTypeName)
+}

altsrc/toml_command_test.go

@@ -0,0 +1,310 @@
+// Disabling building of toml support in cases where golang is 1.0 or 1.1
+// as the encoding library is not implemented or supported.
+
+// +build go1.2
+
+package altsrc
+
+import (
+	"flag"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+func TestCommandTomFileTest(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("test = 15"), 0666)
+	defer os.Remove("current.toml")
+	test := []string{"test-cmd", "--load", "current.toml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileTestGlobalEnvVarWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("test = 15"), 0666)
+	defer os.Remove("current.toml")
+
+	os.Setenv("THE_TEST", "10")
+	defer os.Setenv("THE_TEST", "")
+	test := []string{"test-cmd", "--load", "current.toml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 10)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileTestGlobalEnvVarWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("[top]\ntest = 15"), 0666)
+	defer os.Remove("current.toml")
+
+	os.Setenv("THE_TEST", "10")
+	defer os.Setenv("THE_TEST", "")
+	test := []string{"test-cmd", "--load", "current.toml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 10)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileTestSpecifiedFlagWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("test = 15"), 0666)
+	defer os.Remove("current.toml")
+
+	test := []string{"test-cmd", "--load", "current.toml", "--test", "7"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 7)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileTestSpecifiedFlagWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte(`[top]
+  test = 15`), 0666)
+	defer os.Remove("current.toml")
+
+	test := []string{"test-cmd", "--load", "current.toml", "--top.test", "7"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 7)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileTestDefaultValueFileWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("test = 15"), 0666)
+	defer os.Remove("current.toml")
+
+	test := []string{"test-cmd", "--load", "current.toml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", Value: 7}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileTestDefaultValueFileWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("[top]\ntest = 15"), 0666)
+	defer os.Remove("current.toml")
+
+	test := []string{"test-cmd", "--load", "current.toml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", Value: 7}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileFlagHasDefaultGlobalEnvTomlSetGlobalEnvWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("test = 15"), 0666)
+	defer os.Remove("current.toml")
+
+	os.Setenv("THE_TEST", "11")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", "current.toml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 11)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", Value: 7, EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandTomlFileFlagHasDefaultGlobalEnvTomlSetGlobalEnvWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.toml", []byte("[top]\ntest = 15"), 0666)
+	defer os.Remove("current.toml")
+
+	os.Setenv("THE_TEST", "11")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", "current.toml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 11)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", Value: 7, EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewTomlSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}

altsrc/toml_file_loader.go

@@ -0,0 +1,113 @@
+// Disabling building of toml support in cases where golang is 1.0 or 1.1
+// as the encoding library is not implemented or supported.
+
+// +build go1.2
+
+package altsrc
+
+import (
+	"fmt"
+	"reflect"
+
+	"github.com/BurntSushi/toml"
+	"gopkg.in/urfave/cli.v1"
+)
+
+type tomlMap struct {
+	Map map[interface{}]interface{}
+}
+
+func unmarshalMap(i interface{}) (ret map[interface{}]interface{}, err error) {
+	ret = make(map[interface{}]interface{})
+	m := i.(map[string]interface{})
+	for key, val := range m {
+		v := reflect.ValueOf(val)
+		switch v.Kind() {
+		case reflect.Bool:
+			ret[key] = val.(bool)
+		case reflect.String:
+			ret[key] = val.(string)
+		case reflect.Int:
+			ret[key] = int(val.(int))
+		case reflect.Int8:
+			ret[key] = int(val.(int8))
+		case reflect.Int16:
+			ret[key] = int(val.(int16))
+		case reflect.Int32:
+			ret[key] = int(val.(int32))
+		case reflect.Int64:
+			ret[key] = int(val.(int64))
+		case reflect.Uint:
+			ret[key] = int(val.(uint))
+		case reflect.Uint8:
+			ret[key] = int(val.(uint8))
+		case reflect.Uint16:
+			ret[key] = int(val.(uint16))
+		case reflect.Uint32:
+			ret[key] = int(val.(uint32))
+		case reflect.Uint64:
+			ret[key] = int(val.(uint64))
+		case reflect.Float32:
+			ret[key] = float64(val.(float32))
+		case reflect.Float64:
+			ret[key] = float64(val.(float64))
+		case reflect.Map:
+			if tmp, err := unmarshalMap(val); err == nil {
+				ret[key] = tmp
+			} else {
+				return nil, err
+			}
+		case reflect.Array, reflect.Slice:
+			ret[key] = val.([]interface{})
+		default:
+			return nil, fmt.Errorf("Unsupported: type = %#v", v.Kind())
+		}
+	}
+	return ret, nil
+}
+
+func (tm *tomlMap) UnmarshalTOML(i interface{}) error {
+	if tmp, err := unmarshalMap(i); err == nil {
+		tm.Map = tmp
+	} else {
+		return err
+	}
+	return nil
+}
+
+type tomlSourceContext struct {
+	FilePath string
+}
+
+// NewTomlSourceFromFile creates a new TOML InputSourceContext from a filepath.
+func NewTomlSourceFromFile(file string) (InputSourceContext, error) {
+	tsc := &tomlSourceContext{FilePath: file}
+	var results tomlMap = tomlMap{}
+	if err := readCommandToml(tsc.FilePath, &results); err != nil {
+		return nil, fmt.Errorf("Unable to load TOML file '%s': inner error: \n'%v'", tsc.FilePath, err.Error())
+	}
+	return &MapInputSource{valueMap: results.Map}, nil
+}
+
+// NewTomlSourceFromFlagFunc creates a new TOML InputSourceContext from a provided flag name and source context.
+func NewTomlSourceFromFlagFunc(flagFileName string) func(context *cli.Context) (InputSourceContext, error) {
+	return func(context *cli.Context) (InputSourceContext, error) {
+		filePath := context.String(flagFileName)
+		return NewTomlSourceFromFile(filePath)
+	}
+}
+
+func readCommandToml(filePath string, container interface{}) (err error) {
+	b, err := loadDataFrom(filePath)
+	if err != nil {
+		return err
+	}
+
+	err = toml.Unmarshal(b, container)
+	if err != nil {
+		return err
+	}
+
+	err = nil
+	return
+}

altsrc/yaml_command_test.go

@@ -0,0 +1,313 @@
+// Disabling building of yaml support in cases where golang is 1.0 or 1.1
+// as the encoding library is not implemented or supported.
+
+// +build go1.2
+
+package altsrc
+
+import (
+	"flag"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"gopkg.in/urfave/cli.v1"
+)
+
+func TestCommandYamlFileTest(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte("test: 15"), 0666)
+	defer os.Remove("current.yaml")
+	test := []string{"test-cmd", "--load", "current.yaml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileTestGlobalEnvVarWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte("test: 15"), 0666)
+	defer os.Remove("current.yaml")
+
+	os.Setenv("THE_TEST", "10")
+	defer os.Setenv("THE_TEST", "")
+	test := []string{"test-cmd", "--load", "current.yaml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 10)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileTestGlobalEnvVarWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte(`top:
+  test: 15`), 0666)
+	defer os.Remove("current.yaml")
+
+	os.Setenv("THE_TEST", "10")
+	defer os.Setenv("THE_TEST", "")
+	test := []string{"test-cmd", "--load", "current.yaml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 10)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileTestSpecifiedFlagWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte("test: 15"), 0666)
+	defer os.Remove("current.yaml")
+
+	test := []string{"test-cmd", "--load", "current.yaml", "--test", "7"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 7)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileTestSpecifiedFlagWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte(`top:
+  test: 15`), 0666)
+	defer os.Remove("current.yaml")
+
+	test := []string{"test-cmd", "--load", "current.yaml", "--top.test", "7"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 7)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileTestDefaultValueFileWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte("test: 15"), 0666)
+	defer os.Remove("current.yaml")
+
+	test := []string{"test-cmd", "--load", "current.yaml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", Value: 7}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileTestDefaultValueFileWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte(`top:
+  test: 15`), 0666)
+	defer os.Remove("current.yaml")
+
+	test := []string{"test-cmd", "--load", "current.yaml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 15)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", Value: 7}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileFlagHasDefaultGlobalEnvYamlSetGlobalEnvWins(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte("test: 15"), 0666)
+	defer os.Remove("current.yaml")
+
+	os.Setenv("THE_TEST", "11")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", "current.yaml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("test")
+			expect(t, val, 11)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "test", Value: 7, EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}
+
+func TestCommandYamlFileFlagHasDefaultGlobalEnvYamlSetGlobalEnvWinsNested(t *testing.T) {
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	ioutil.WriteFile("current.yaml", []byte(`top:
+  test: 15`), 0666)
+	defer os.Remove("current.yaml")
+
+	os.Setenv("THE_TEST", "11")
+	defer os.Setenv("THE_TEST", "")
+
+	test := []string{"test-cmd", "--load", "current.yaml"}
+	set.Parse(test)
+
+	c := cli.NewContext(app, set, nil)
+
+	command := &cli.Command{
+		Name:        "test-cmd",
+		Aliases:     []string{"tc"},
+		Usage:       "this is for testing",
+		Description: "testing",
+		Action: func(c *cli.Context) error {
+			val := c.Int("top.test")
+			expect(t, val, 11)
+			return nil
+		},
+		Flags: []cli.Flag{
+			NewIntFlag(cli.IntFlag{Name: "top.test", Value: 7, EnvVar: "THE_TEST"}),
+			cli.StringFlag{Name: "load"}},
+	}
+	command.Before = InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load"))
+	err := command.Run(c)
+
+	expect(t, err, nil)
+}

altsrc/yaml_file_loader.go

@@ -0,0 +1,92 @@
+// Disabling building of yaml support in cases where golang is 1.0 or 1.1
+// as the encoding library is not implemented or supported.
+
+// +build go1.2
+
+package altsrc
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"os"
+	"runtime"
+	"strings"
+
+	"gopkg.in/urfave/cli.v1"
+
+	"gopkg.in/yaml.v2"
+)
+
+type yamlSourceContext struct {
+	FilePath string
+}
+
+// NewYamlSourceFromFile creates a new Yaml InputSourceContext from a filepath.
+func NewYamlSourceFromFile(file string) (InputSourceContext, error) {
+	ysc := &yamlSourceContext{FilePath: file}
+	var results map[interface{}]interface{}
+	err := readCommandYaml(ysc.FilePath, &results)
+	if err != nil {
+		return nil, fmt.Errorf("Unable to load Yaml file '%s': inner error: \n'%v'", ysc.FilePath, err.Error())
+	}
+
+	return &MapInputSource{valueMap: results}, nil
+}
+
+// NewYamlSourceFromFlagFunc creates a new Yaml InputSourceContext from a provided flag name and source context.
+func NewYamlSourceFromFlagFunc(flagFileName string) func(context *cli.Context) (InputSourceContext, error) {
+	return func(context *cli.Context) (InputSourceContext, error) {
+		filePath := context.String(flagFileName)
+		return NewYamlSourceFromFile(filePath)
+	}
+}
+
+func readCommandYaml(filePath string, container interface{}) (err error) {
+	b, err := loadDataFrom(filePath)
+	if err != nil {
+		return err
+	}
+
+	err = yaml.Unmarshal(b, container)
+	if err != nil {
+		return err
+	}
+
+	err = nil
+	return
+}
+
+func loadDataFrom(filePath string) ([]byte, error) {
+	u, err := url.Parse(filePath)
+	if err != nil {
+		return nil, err
+	}
+
+	if u.Host != "" { // i have a host, now do i support the scheme?
+		switch u.Scheme {
+		case "http", "https":
+			res, err := http.Get(filePath)
+			if err != nil {
+				return nil, err
+			}
+			return ioutil.ReadAll(res.Body)
+		default:
+			return nil, fmt.Errorf("scheme of %s is unsupported", filePath)
+		}
+	} else if u.Path != "" { // i dont have a host, but I have a path. I am a local file.
+		if _, notFoundFileErr := os.Stat(filePath); notFoundFileErr != nil {
+			return nil, fmt.Errorf("Cannot read from file: '%s' because it does not exist.", filePath)
+		}
+		return ioutil.ReadFile(filePath)
+	} else if runtime.GOOS == "windows" && strings.Contains(u.String(), "\\") {
+		// on Windows systems u.Path is always empty, so we need to check the string directly.
+		if _, notFoundFileErr := os.Stat(filePath); notFoundFileErr != nil {
+			return nil, fmt.Errorf("Cannot read from file: '%s' because it does not exist.", filePath)
+		}
+		return ioutil.ReadFile(filePath)
+	}
+
+	return nil, fmt.Errorf("unable to determine how to load from path %s", filePath)
+}

app.go

@@ -5,20 +5,40 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
-	"text/tabwriter"
+	"path/filepath"
-	"text/template"
+	"sort"
 	"time"
 )
 
-// App is the main structure of a cli application. It is recomended that
+var (
-// and app be created with the cli.NewApp() function
+	changeLogURL                    = "https://github.com/urfave/cli/blob/master/CHANGELOG.md"
+	appActionDeprecationURL         = fmt.Sprintf("%s#deprecated-cli-app-action-signature", changeLogURL)
+	runAndExitOnErrorDeprecationURL = fmt.Sprintf("%s#deprecated-cli-app-runandexitonerror", changeLogURL)
+
+	contactSysadmin = "This is an error in the application.  Please contact the distributor of this application if this is not you."
+
+	errInvalidActionType = NewExitError("ERROR invalid Action type. "+
+		fmt.Sprintf("Must be `func(*Context`)` or `func(*Context) error).  %s", contactSysadmin)+
+		fmt.Sprintf("See %s", appActionDeprecationURL), 2)
+)
+
+// App is the main structure of a cli application. It is recommended that
+// an app be created with the cli.NewApp() function
 type App struct {
-	// The name of the program. Defaults to os.Args[0]
+	// The name of the program. Defaults to path.Base(os.Args[0])
 	Name string
+	// Full name of command for help, defaults to Name
+	HelpName string
 	// Description of the program.
 	Usage string
+	// Text to override the USAGE section of help
+	UsageText string
+	// Description of the program argument format.
+	ArgsUsage string
 	// Version of the program
 	Version string
+	// Description of the program
+	Description string
 	// List of commands to execute
 	Commands []Command
 	// List of flags to parse
@@ -27,28 +47,55 @@ type App struct {
 	EnableBashCompletion bool
 	// Boolean to hide built-in help command
 	HideHelp bool
-	// Boolean to hide built-in version flag
+	// Boolean to hide built-in version flag and the VERSION section of help
 	HideVersion bool
+	// Populate on app startup, only gettable through method Categories()
+	categories CommandCategories
 	// An action to execute when the bash-completion flag is set
-	BashComplete func(context *Context)
+	BashComplete BashCompleteFunc
 	// An action to execute before any subcommands are run, but after the context is ready
 	// If a non-nil error is returned, no subcommands are run
-	Before func(context *Context) error
+	Before BeforeFunc
 	// An action to execute after any subcommands are run, but after the subcommand has finished
 	// It is run even if Action() panics
-	After func(context *Context) error
+	After AfterFunc
+
 	// The action to execute when no subcommands are specified
-	Action func(context *Context)
+	// Expects a `cli.ActionFunc` but will accept the *deprecated* signature of `func(*cli.Context) {}`
+	// *Note*: support for the deprecated `Action` signature will be removed in a future version
+	Action interface{}
+
 	// Execute this function if the proper command cannot be found
-	CommandNotFound func(context *Context, command string)
+	CommandNotFound CommandNotFoundFunc
+	// Execute this function if an usage error occurs
+	OnUsageError OnUsageErrorFunc
 	// Compilation date
 	Compiled time.Time
-	// Author
+	// List of all authors who contributed
+	Authors []Author
+	// Copyright of the binary if any
+	Copyright string
+	// Name of Author (Note: Use App.Authors, this is deprecated)
 	Author string
-	// Author e-mail
+	// Email of Author (Note: Use App.Authors, this is deprecated)
 	Email string
 	// Writer writer to write output to
 	Writer io.Writer
+	// ErrWriter writes error output
+	ErrWriter io.Writer
+	// Execute this function to handle ExitErrors. If not provided, HandleExitCoder is provided to
+	// function as a default, so this is optional.
+	ExitErrHandler ExitErrHandlerFunc
+	// Other custom info
+	Metadata map[string]interface{}
+	// Carries a function which returns app specific info.
+	ExtraInfo func() map[string]string
+	// CustomAppHelpTemplate the text template for app help topic.
+	// cli.go uses text/template to render templates. You can
+	// render custom help text by setting this variable.
+	CustomAppHelpTemplate string
+
+	didSetup bool
 }
 
 // Tries to find out when this binary was compiled.
@@ -61,40 +108,45 @@ func compileTime() time.Time {
 	return info.ModTime()
 }
 
-// Creates a new cli Application with some reasonable defaults for Name, Usage, Version and Action.
+// NewApp creates a new cli Application with some reasonable defaults for Name,
+// Usage, Version and Action.
 func NewApp() *App {
 	return &App{
-		Name:         os.Args[0],
+		Name:         filepath.Base(os.Args[0]),
+		HelpName:     filepath.Base(os.Args[0]),
 		Usage:        "A new cli application",
+		UsageText:    "",
 		Version:      "0.0.0",
 		BashComplete: DefaultAppComplete,
 		Action:       helpCommand.Action,
 		Compiled:     compileTime(),
-		Author:       "Author",
-		Email:        "unknown@email",
 		Writer:       os.Stdout,
 	}
 }
 
-// Entry point to the cli app. Parses the arguments slice and routes to the proper flag/args combination
+// Setup runs initialization code to ensure all data structures are ready for
-func (a *App) Run(arguments []string) (err error) {
+// `Run` or inspection prior to `Run`.  It is internally called by `Run`, but
-	if HelpPrinter == nil {
+// will return early if setup has already happened.
-		defer func() {
+func (a *App) Setup() {
-			HelpPrinter = nil
+	if a.didSetup {
-		}()
+		return
-
-		HelpPrinter = func(templ string, data interface{}) {
-			w := tabwriter.NewWriter(a.Writer, 0, 8, 1, '\t', 0)
-			t := template.Must(template.New("help").Parse(templ))
-			err := t.Execute(w, data)
-			if err != nil {
-				panic(err)
-			}
-			w.Flush()
-		}
 	}
 
-	// append help to commands
+	a.didSetup = true
+
+	if a.Author != "" || a.Email != "" {
+		a.Authors = append(a.Authors, Author{Name: a.Author, Email: a.Email})
+	}
+
+	newCmds := []Command{}
+	for _, c := range a.Commands {
+		if c.HelpName == "" {
+			c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
+		}
+		newCmds = append(newCmds, c)
+	}
+	a.Commands = newCmds
+
 	if a.Command(helpCommand.Name) == nil && !a.HideHelp {
 		a.Commands = append(a.Commands, helpCommand)
 		if (HelpFlag != BoolFlag{}) {
@@ -102,23 +154,50 @@ func (a *App) Run(arguments []string) (err error) {
 		}
 	}
 
-	//append version/help flags
-	if a.EnableBashCompletion {
-		a.appendFlag(BashCompletionFlag)
-	}
-
 	if !a.HideVersion {
 		a.appendFlag(VersionFlag)
 	}
 
+	a.categories = CommandCategories{}
+	for _, command := range a.Commands {
+		a.categories = a.categories.AddCommand(command.Category, command)
+	}
+	sort.Sort(a.categories)
+
+	if a.Metadata == nil {
+		a.Metadata = make(map[string]interface{})
+	}
+
+	if a.Writer == nil {
+		a.Writer = os.Stdout
+	}
+}
+
+// Run is the entry point to the cli app. Parses the arguments slice and routes
+// to the proper flag/args combination
+func (a *App) Run(arguments []string) (err error) {
+	a.Setup()
+
+	// handle the completion flag separately from the flagset since
+	// completion could be attempted after a flag, but before its value was put
+	// on the command line. this causes the flagset to interpret the completion
+	// flag name as the value of the flag before it which is undesirable
+	// note that we can only do this because the shell autocomplete function
+	// always appends the completion flag at the end of the command
+	shellComplete, arguments := checkShellCompleteFlag(a, arguments)
+
 	// parse flags
-	set := flagSet(a.Name, a.Flags)
+	set, err := flagSet(a.Name, a.Flags)
+	if err != nil {
+		return err
+	}
+
 	set.SetOutput(ioutil.Discard)
 	err = set.Parse(arguments[1:])
 	nerr := normalizeFlags(a.Flags, set)
 	cerr := checkRequiredFlags(a.Flags, set)
 
-	context := NewContext(a, set, set)
+	context := NewContext(a, set, nil)
 
 	// Define here so it closes over the above variables
 	showErrAndHelp := func(err error) {
@@ -129,9 +208,15 @@ func (a *App) Run(arguments []string) (err error) {
 	}
 
 	if nerr != nil {
-		showErrAndHelp(nerr)
+		fmt.Fprintln(a.Writer, nerr)
+		ShowAppHelp(context)
 		return nerr
 	}
+	context.shellComplete = shellComplete
+
+	if checkCompletions(context) {
+		return nil
+	}
 
 	if cerr != nil {
 		showErrAndHelp(cerr)
@@ -139,34 +224,45 @@ func (a *App) Run(arguments []string) (err error) {
 	}
 
 	if err != nil {
-		showErrAndHelp(fmt.Errorf("Incorrect Usage."))
+		if a.OnUsageError != nil {
+			err := a.OnUsageError(context, err, false)
+			a.handleExitCoder(context, err)
+			return err
+		}
+		fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
+		ShowAppHelp(context)
 		return err
 	}
 
-	if checkCompletions(context) {
+	if !a.HideHelp && checkHelp(context) {
+		ShowAppHelp(context)
 		return nil
 	}
 
-	if checkHelp(context) {
+	if !a.HideVersion && checkVersion(context) {
-		return nil
+		ShowVersion(context)
-	}
-
-	if checkVersion(context) {
 		return nil
 	}
 
 	if a.After != nil {
 		defer func() {
-			// err is always nil here.
+			if afterErr := a.After(context); afterErr != nil {
-			// There is a check to see if it is non-nil
+				if err != nil {
-			// just few lines before.
+					err = NewMultiError(err, afterErr)
-			err = a.After(context)
+				} else {
+					err = afterErr
+				}
+			}
 		}()
 	}
 
 	if a.Before != nil {
-		err := a.Before(context)
+		beforeErr := a.Before(context)
-		if err != nil {
+		if beforeErr != nil {
+			fmt.Fprintf(a.Writer, "%v\n\n", beforeErr)
+			ShowAppHelp(context)
+			a.handleExitCoder(context, beforeErr)
+			err = beforeErr
 			return err
 		}
 	}
@@ -180,20 +276,31 @@ func (a *App) Run(arguments []string) (err error) {
 		}
 	}
 
+	if a.Action == nil {
+		a.Action = helpCommand.Action
+	}
+
 	// Run default Action
-	a.Action(context)
+	err = HandleAction(a.Action, context)
-	return nil
+
+	a.handleExitCoder(context, err)
+	return err
 }
 
-// Another entry point to the cli app, takes care of passing arguments and error handling
+// RunAndExitOnError calls .Run() and exits non-zero if an error was returned
+//
+// Deprecated: instead you should return an error that fulfills cli.ExitCoder
+// to cli.App.Run. This will cause the application to exit with the given eror
+// code in the cli.ExitCoder
 func (a *App) RunAndExitOnError() {
 	if err := a.Run(os.Args); err != nil {
-		fmt.Fprintln(os.Stderr, err)
+		fmt.Fprintln(a.errWriter(), err)
-		os.Exit(1)
+		OsExiter(1)
 	}
 }
 
-// Invokes the subcommand given the context, parses ctx.Args() to generate command-specific flags
+// RunAsSubcommand invokes the subcommand given the context, parses ctx.Args() to
+// generate command-specific flags
 func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 	// append help to commands
 	if len(a.Commands) > 0 {
@@ -205,23 +312,29 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 		}
 	}
 
-	// append flags
+	newCmds := []Command{}
-	if a.EnableBashCompletion {
+	for _, c := range a.Commands {
-		a.appendFlag(BashCompletionFlag)
+		if c.HelpName == "" {
+			c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
+		}
+		newCmds = append(newCmds, c)
 	}
+	a.Commands = newCmds
 
 	// parse flags
-	set := flagSet(a.Name, a.Flags)
+	set, err := flagSet(a.Name, a.Flags)
+	if err != nil {
+		return err
+	}
+
 	set.SetOutput(ioutil.Discard)
 	err = set.Parse(ctx.Args().Tail())
 	nerr := normalizeFlags(a.Flags, set)
 	cerr := checkRequiredFlags(a.Flags, set)
+	context := NewContext(a, set, ctx)
 
-	context := NewContext(a, set, ctx.globalSet)
+	if nerr != nil {
-
+		fmt.Fprintln(a.Writer, nerr)
-	// Define here so it closes over the above variables
-	showErrAndHelp := func(err error) {
-		fmt.Fprintln(a.Writer, err)
 		fmt.Fprintln(a.Writer)
 		if len(a.Commands) > 0 {
 			ShowSubcommandHelp(context)
@@ -231,25 +344,26 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 		fmt.Fprintln(a.Writer, err)
 	}
 
-	if nerr != nil {
-		showErrAndHelp(nerr)
-		return nerr
-	}
-
 	if cerr != nil {
 		showErrAndHelp(cerr)
 		return cerr
 	}
 
-	if err != nil {
-		showErrAndHelp(err)
-		return err
-	}
-
 	if checkCompletions(context) {
 		return nil
 	}
 
+	if err != nil {
+		if a.OnUsageError != nil {
+			err = a.OnUsageError(context, err, true)
+			a.handleExitCoder(context, err)
+			return err
+		}
+		fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
+		ShowSubcommandHelp(context)
+		return err
+	}
+
 	if len(a.Commands) > 0 {
 		if checkSubcommandHelp(context) {
 			return nil
@@ -262,16 +376,23 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 
 	if a.After != nil {
 		defer func() {
-			// err is always nil here.
+			afterErr := a.After(context)
-			// There is a check to see if it is non-nil
+			if afterErr != nil {
-			// just few lines before.
+				a.handleExitCoder(context, err)
-			err = a.After(context)
+				if err != nil {
+					err = NewMultiError(err, afterErr)
+				} else {
+					err = afterErr
+				}
+			}
 		}()
 	}
 
 	if a.Before != nil {
-		err := a.Before(context)
+		beforeErr := a.Before(context)
-		if err != nil {
+		if beforeErr != nil {
+			a.handleExitCoder(context, beforeErr)
+			err = beforeErr
 			return err
 		}
 	}
@@ -286,12 +407,13 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 	}
 
 	// Run default Action
-	a.Action(context)
+	err = HandleAction(a.Action, context)
 
-	return nil
+	a.handleExitCoder(context, err)
+	return err
 }
 
-// Returns the named command on App. Returns nil if the command does not exist
+// Command returns the named command on App. Returns nil if the command does not exist
 func (a *App) Command(name string) *Command {
 	for _, c := range a.Commands {
 		if c.HasName(name) {
@@ -302,6 +424,46 @@ func (a *App) Command(name string) *Command {
 	return nil
 }
 
+// Categories returns a slice containing all the categories with the commands they contain
+func (a *App) Categories() CommandCategories {
+	return a.categories
+}
+
+// VisibleCategories returns a slice of categories and commands that are
+// Hidden=false
+func (a *App) VisibleCategories() []*CommandCategory {
+	ret := []*CommandCategory{}
+	for _, category := range a.categories {
+		if visible := func() *CommandCategory {
+			for _, command := range category.Commands {
+				if !command.Hidden {
+					return category
+				}
+			}
+			return nil
+		}(); visible != nil {
+			ret = append(ret, visible)
+		}
+	}
+	return ret
+}
+
+// VisibleCommands returns a slice of the Commands with Hidden=false
+func (a *App) VisibleCommands() []Command {
+	ret := []Command{}
+	for _, command := range a.Commands {
+		if !command.Hidden {
+			ret = append(ret, command)
+		}
+	}
+	return ret
+}
+
+// VisibleFlags returns a slice of the Flags with Hidden=false
+func (a *App) VisibleFlags() []Flag {
+	return visibleFlags(a.Flags)
+}
+
 func (a *App) hasFlag(flag Flag) bool {
 	for _, f := range a.Flags {
 		if flag == f {
@@ -312,8 +474,58 @@ func (a *App) hasFlag(flag Flag) bool {
 	return false
 }
 
+func (a *App) errWriter() io.Writer {
+	// When the app ErrWriter is nil use the package level one.
+	if a.ErrWriter == nil {
+		return ErrWriter
+	}
+
+	return a.ErrWriter
+}
+
 func (a *App) appendFlag(flag Flag) {
 	if !a.hasFlag(flag) {
 		a.Flags = append(a.Flags, flag)
 	}
 }
+
+func (a *App) handleExitCoder(context *Context, err error) {
+	if a.ExitErrHandler != nil {
+		a.ExitErrHandler(context, err)
+	} else {
+		HandleExitCoder(err)
+	}
+}
+
+// Author represents someone who has contributed to a cli project.
+type Author struct {
+	Name  string // The Authors name
+	Email string // The Authors email
+}
+
+// String makes Author comply to the Stringer interface, to allow an easy print in the templating process
+func (a Author) String() string {
+	e := ""
+	if a.Email != "" {
+		e = " <" + a.Email + ">"
+	}
+
+	return fmt.Sprintf("%v%v", a.Name, e)
+}
+
+// HandleAction attempts to figure out which Action signature was used.  If
+// it's an ActionFunc or a func with the legacy signature for Action, the func
+// is run!
+func HandleAction(action interface{}, context *Context) (err error) {
+	switch a := action.(type) {
+	case ActionFunc:
+		return a(context)
+	case func(*Context) error:
+		return a(context)
+	case func(*Context): // deprecated function signature
+		a(context)
+		return nil
+	}
+
+	return errInvalidActionType
+}

appveyor.yml

@@ -0,0 +1,26 @@
+version: "{build}"
+
+os: Windows Server 2016
+
+image: Visual Studio 2017
+
+clone_folder: c:\gopath\src\github.com\urfave\cli
+
+environment:
+  GOPATH: C:\gopath
+  GOVERSION: 1.8.x
+  PYTHON: C:\Python36-x64
+  PYTHON_VERSION: 3.6.x
+  PYTHON_ARCH: 64
+
+install:
+- set PATH=%GOPATH%\bin;C:\go\bin;%PATH%
+- go version
+- go env
+- go get github.com/urfave/gfmrun/...
+- go get -v -t ./...
+
+build_script:
+- python runtests vet
+- python runtests test
+- python runtests gfmrun

autocomplete/bash_autocomplete

@@ -1,13 +1,16 @@
 #! /bin/bash
 
+: ${PROG:=$(basename ${BASH_SOURCE})}
+
 _cli_bash_autocomplete() {
-     local cur prev opts base
+    local cur opts base
-     COMPREPLY=()
+    COMPREPLY=()
-     cur="${COMP_WORDS[COMP_CWORD]}"
+    cur="${COMP_WORDS[COMP_CWORD]}"
-     prev="${COMP_WORDS[COMP_CWORD-1]}"
+    opts=$( ${COMP_WORDS[@]:0:$COMP_CWORD} --generate-bash-completion )
-     opts=$( ${COMP_WORDS[@]:0:$COMP_CWORD} --generate-bash-completion )
+    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
-     COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
+    return 0
-     return 0
+}
- }
+
-  
+complete -F _cli_bash_autocomplete $PROG
- complete -F _cli_bash_autocomplete $PROG
+
+unset PROG

autocomplete/zsh_autocomplete

@@ -1,5 +1,11 @@
-autoload -U compinit && compinit
+_cli_zsh_autocomplete() {
-autoload -U bashcompinit && bashcompinit
 
-script_dir=$(dirname $0)
+  local -a opts
-source ${script_dir}/bash_autocomplete
+  opts=("${(@f)$(_CLI_ZSH_AUTOCOMPLETE_HACK=1 ${words[@]:0:#words[@]-1} --generate-bash-completion)}")
+
+  _describe 'values' opts
+
+  return
+}
+
+compdef _cli_zsh_autocomplete $PROG

category.go

@@ -0,0 +1,44 @@
+package cli
+
+// CommandCategories is a slice of *CommandCategory.
+type CommandCategories []*CommandCategory
+
+// CommandCategory is a category containing commands.
+type CommandCategory struct {
+	Name     string
+	Commands Commands
+}
+
+func (c CommandCategories) Less(i, j int) bool {
+	return lexicographicLess(c[i].Name, c[j].Name)
+}
+
+func (c CommandCategories) Len() int {
+	return len(c)
+}
+
+func (c CommandCategories) Swap(i, j int) {
+	c[i], c[j] = c[j], c[i]
+}
+
+// AddCommand adds a command to a category.
+func (c CommandCategories) AddCommand(category string, command Command) CommandCategories {
+	for _, commandCategory := range c {
+		if commandCategory.Name == category {
+			commandCategory.Commands = append(commandCategory.Commands, command)
+			return c
+		}
+	}
+	return append(c, &CommandCategory{Name: category, Commands: []Command{command}})
+}
+
+// VisibleCommands returns a slice of the Commands with Hidden=false
+func (c *CommandCategory) VisibleCommands() []Command {
+	ret := []Command{}
+	for _, command := range c.Commands {
+		if !command.Hidden {
+			ret = append(ret, command)
+		}
+	}
+	return ret
+}

cli.go

@@ -10,10 +10,13 @@
 //     app := cli.NewApp()
 //     app.Name = "greet"
 //     app.Usage = "say a greeting"
-//     app.Action = func(c *cli.Context) {
+//     app.Action = func(c *cli.Context) error {
 //       println("Greetings")
+//       return nil
 //     }
 //
 //     app.Run(os.Args)
 //   }
 package cli
+
+//go:generate python ./generate-flag-types cli -i flag-types.json -o flag_generated.go

cli_test.go

@@ -1,100 +0,0 @@
-package cli_test
-
-import (
-	"os"
-
-	"github.com/codegangsta/cli"
-)
-
-func Example() {
-	app := cli.NewApp()
-	app.Name = "todo"
-	app.Usage = "task list on the command line"
-	app.Commands = []cli.Command{
-		{
-			Name:      "add",
-			ShortName: "a",
-			Usage:     "add a task to the list",
-			Action: func(c *cli.Context) {
-				println("added task: ", c.Args().First())
-			},
-		},
-		{
-			Name:      "complete",
-			ShortName: "c",
-			Usage:     "complete a task on the list",
-			Action: func(c *cli.Context) {
-				println("completed task: ", c.Args().First())
-			},
-		},
-	}
-
-	app.Run(os.Args)
-}
-
-func ExampleSubcommand() {
-	app := cli.NewApp()
-	app.Name = "say"
-	app.Commands = []cli.Command{
-		{
-			Name:        "hello",
-			ShortName:   "hi",
-			Usage:       "use it to see a description",
-			Description: "This is how we describe hello the function",
-			Subcommands: []cli.Command{
-				{
-					Name:        "english",
-					ShortName:   "en",
-					Usage:       "sends a greeting in english",
-					Description: "greets someone in english",
-					Flags: []cli.Flag{
-						cli.StringFlag{
-							Name:  "name",
-							Value: "Bob",
-							Usage: "Name of the person to greet",
-						},
-					},
-					Action: func(c *cli.Context) {
-						println("Hello, ", c.String("name"))
-					},
-				}, {
-					Name:      "spanish",
-					ShortName: "sp",
-					Usage:     "sends a greeting in spanish",
-					Flags: []cli.Flag{
-						cli.StringFlag{
-							Name:  "surname",
-							Value: "Jones",
-							Usage: "Surname of the person to greet",
-						},
-					},
-					Action: func(c *cli.Context) {
-						println("Hola, ", c.String("surname"))
-					},
-				}, {
-					Name:      "french",
-					ShortName: "fr",
-					Usage:     "sends a greeting in french",
-					Flags: []cli.Flag{
-						cli.StringFlag{
-							Name:  "nickname",
-							Value: "Stevie",
-							Usage: "Nickname of the person to greet",
-						},
-					},
-					Action: func(c *cli.Context) {
-						println("Bonjour, ", c.String("nickname"))
-					},
-				},
-			},
-		}, {
-			Name:  "bye",
-			Usage: "says goodbye",
-			Action: func(c *cli.Context) {
-				println("bye")
-			},
-		},
-	}
-
-	app.Run(os.Args)
-}

command.go

@@ -1,8 +1,10 @@
 package cli
 
 import (
+	"flag"
 	"fmt"
 	"io/ioutil"
+	"sort"
 	"strings"
 )
 
@@ -10,36 +12,94 @@ import (
 type Command struct {
 	// The name of the command
 	Name string
-	// short name of the command. Typically one character
+	// short name of the command. Typically one character (deprecated, use `Aliases`)
 	ShortName string
+	// A list of aliases for the command
+	Aliases []string
 	// A short description of the usage of this command
 	Usage string
+	// Custom text to show on USAGE section of help
+	UsageText string
 	// A longer explanation of how the command works
 	Description string
+	// A short description of the arguments of this command
+	ArgsUsage string
+	// The category the command is part of
+	Category string
 	// The function to call when checking for bash command completions
-	BashComplete func(context *Context)
+	BashComplete BashCompleteFunc
 	// An action to execute before any sub-subcommands are run, but after the context is ready
 	// If a non-nil error is returned, no sub-subcommands are run
-	Before func(context *Context) error
+	Before BeforeFunc
 	// An action to execute after any subcommands are run, but after the subcommand has finished
 	// It is run even if Action() panics
-	After func(context *Context) error
+	After AfterFunc
 	// The function to call when this command is invoked
-	Action func(context *Context)
+	Action interface{}
+	// TODO: replace `Action: interface{}` with `Action: ActionFunc` once some kind
+	// of deprecation period has passed, maybe?
+
+	// Execute this function if a usage error occurs.
+	OnUsageError OnUsageErrorFunc
 	// List of child commands
-	Subcommands []Command
+	Subcommands Commands
 	// List of flags to parse
 	Flags []Flag
 	// Treat all flags as normal arguments if true
 	SkipFlagParsing bool
+	// Skip argument reordering which attempts to move flags before arguments,
+	// but only works if all flags appear after all arguments. This behavior was
+	// removed n version 2 since it only works under specific conditions so we
+	// backport here by exposing it as an option for compatibility.
+	SkipArgReorder bool
 	// Boolean to hide built-in help command
 	HideHelp bool
+	// Boolean to hide this command from help or completion
+	Hidden bool
+	// Boolean to enable short-option handling so user can combine several
+	// single-character bool arguments into one
+	// i.e. foobar -o -v -> foobar -ov
+	UseShortOptionHandling bool
+
+	// Full name of command for help, defaults to full command name, including parent commands.
+	HelpName        string
+	commandNamePath []string
+
+	// CustomHelpTemplate the text template for the command help topic.
+	// cli.go uses text/template to render templates. You can
+	// render custom help text by setting this variable.
+	CustomHelpTemplate string
 }
 
-// Invokes the command given the context, parses ctx.Args() to generate command-specific flags
+type CommandsByName []Command
-func (c Command) Run(ctx *Context) error {
 
-	if len(c.Subcommands) > 0 || c.Before != nil || c.After != nil {
+func (c CommandsByName) Len() int {
+	return len(c)
+}
+
+func (c CommandsByName) Less(i, j int) bool {
+	return lexicographicLess(c[i].Name, c[j].Name)
+}
+
+func (c CommandsByName) Swap(i, j int) {
+	c[i], c[j] = c[j], c[i]
+}
+
+// FullName returns the full name of the command.
+// For subcommands this ensures that parent commands are part of the command path
+func (c Command) FullName() string {
+	if c.commandNamePath == nil {
+		return c.Name
+	}
+	return strings.Join(c.commandNamePath, " ")
+}
+
+// Commands is a slice of Command
+type Commands []Command
+
+// Run invokes the command given the context, parses ctx.Args() to generate command-specific flags
+func (c Command) Run(ctx *Context) (err error) {
+	if len(c.Subcommands) > 0 {
 		return c.startApp(ctx)
 	}
 
@@ -51,41 +111,155 @@ func (c Command) Run(ctx *Context) error {
 		)
 	}
 
-	if ctx.App.EnableBashCompletion {
+	set, err := c.parseFlags(ctx.Args().Tail())
-		c.Flags = append(c.Flags, BashCompletionFlag)
+
+	context := NewContext(ctx.App, set, ctx)
+	context.Command = c
+	if checkCommandCompletions(context, c.Name) {
+		return nil
 	}
 
-	set := flagSet(c.Name, c.Flags)
+	if err != nil {
+		if c.OnUsageError != nil {
+			err := c.OnUsageError(context, err, false)
+			context.App.handleExitCoder(context, err)
+			return err
+		}
+		fmt.Fprintln(context.App.Writer, "Incorrect Usage:", err.Error())
+		fmt.Fprintln(context.App.Writer)
+		ShowCommandHelp(context, c.Name)
+		return err
+	}
+
+	if checkCommandHelp(context, c.Name) {
+		return nil
+	}
+
+	if c.After != nil {
+		defer func() {
+			afterErr := c.After(context)
+			if afterErr != nil {
+				context.App.handleExitCoder(context, err)
+				if err != nil {
+					err = NewMultiError(err, afterErr)
+				} else {
+					err = afterErr
+				}
+			}
+		}()
+	}
+
+	if c.Before != nil {
+		err = c.Before(context)
+		if err != nil {
+			ShowCommandHelp(context, c.Name)
+			context.App.handleExitCoder(context, err)
+			return err
+		}
+	}
+
+	if c.Action == nil {
+		c.Action = helpSubcommand.Action
+	}
+
+	err = HandleAction(c.Action, context)
+
+	if err != nil {
+		context.App.handleExitCoder(context, err)
+	}
+	return err
+}
+
+func (c *Command) parseFlags(args Args) (*flag.FlagSet, error) {
+	set, err := flagSet(c.Name, c.Flags)
+	if err != nil {
+		return nil, err
+	}
 	set.SetOutput(ioutil.Discard)
 
-	firstFlagIndex := -1
+	if c.SkipFlagParsing {
-	terminatorIndex := -1
+		return set, set.Parse(append([]string{"--"}, args...))
-	for index, arg := range ctx.Args() {
-		if arg == "--" {
-			terminatorIndex = index
-			break
-		} else if strings.HasPrefix(arg, "-") && firstFlagIndex == -1 {
-			firstFlagIndex = index
-		}
 	}
 
-	var err error
+	if !c.SkipArgReorder {
-	if firstFlagIndex > -1 && !c.SkipFlagParsing {
+		args = reorderArgs(args)
-		args := ctx.Args()
+	}
-		regularArgs := make([]string, len(args[1:firstFlagIndex]))
-		copy(regularArgs, args[1:firstFlagIndex])
 
-		var flagArgs []string
+PARSE:
-		if terminatorIndex > -1 {
+	err = set.Parse(args)
-			flagArgs = args[firstFlagIndex:terminatorIndex]
+	if err != nil {
-			regularArgs = append(regularArgs, args[terminatorIndex:]...)
+		if c.UseShortOptionHandling {
-		} else {
+			// To enable short-option handling (e.g., "-it" vs "-i -t")
-			flagArgs = args[firstFlagIndex:]
+			// we have to iteratively catch parsing errors.  This way
+			// we achieve LR parsing without transforming any arguments.
+			// Otherwise, there is no way we can discriminate combined
+			// short options from common arguments that should be left
+			// untouched.
+			errStr := err.Error()
+			trimmed := strings.TrimPrefix(errStr, "flag provided but not defined: ")
+			if errStr == trimmed {
+				return nil, err
+			}
+			// regenerate the initial args with the split short opts
+			newArgs := Args{}
+			for i, arg := range args {
+				if arg != trimmed {
+					newArgs = append(newArgs, arg)
+					continue
+				}
+				shortOpts := translateShortOptions(set, Args{trimmed})
+				if len(shortOpts) == 1 {
+					return nil, err
+				}
+				// add each short option and all remaining arguments
+				newArgs = append(newArgs, shortOpts...)
+				newArgs = append(newArgs, args[i+1:]...)
+				args = newArgs
+				// now reset the flagset parse again
+				set, err = flagSet(c.Name, c.Flags)
+				if err != nil {
+					return nil, err
+				}
+				set.SetOutput(ioutil.Discard)
+				goto PARSE
+			}
+		}
+		return nil, err
+	}
+
+	err = normalizeFlags(c.Flags, set)
+	if err != nil {
+		return nil, err
+	}
+
+	return set, nil
+}
+
+// reorderArgs moves all flags before arguments as this is what flag expects
+func reorderArgs(args []string) []string {
+	var nonflags, flags []string
+
+	readFlagValue := false
+	for i, arg := range args {
+		if arg == "--" {
+			nonflags = append(nonflags, args[i:]...)
+			break
 		}
 
-		err = set.Parse(append(flagArgs, regularArgs...))
+		if readFlagValue && !strings.HasPrefix(arg, "-") && !strings.HasPrefix(arg, "--") {
-	} else {
+			readFlagValue = false
-		err = set.Parse(ctx.Args().Tail())
+			flags = append(flags, arg)
+			continue
+		}
+		readFlagValue = false
+
+		if arg != "-" && strings.HasPrefix(arg, "-") {
+			flags = append(flags, arg)
+
+			readFlagValue = !strings.Contains(arg, "=")
+		} else {
+			nonflags = append(nonflags, arg)
+		}
 	}
 
 	// Define here so it closes over the above variables
@@ -114,43 +288,98 @@ func (c Command) Run(ctx *Context) error {
 	}
 
 	context := NewContext(ctx.App, set, ctx.globalSet)
-
+	return append(flags, nonflags...)
-	if checkCommandCompletions(context, c.Name) {
-		return nil
-	}
-
-	if checkCommandHelp(context, c.Name) {
-		return nil
-	}
-	context.Command = c
-	c.Action(context)
-	return nil
 }
 
-// Returns true if Command.Name or Command.ShortName matches given name
+func translateShortOptions(set *flag.FlagSet, flagArgs Args) []string {
+	allCharsFlags := func (s string) bool {
+		for i := range s {
+			f := set.Lookup(string(s[i]))
+			if f == nil {
+				return false
+			}
+		}
+		return true
+	}
+
+	// separate combined flags
+	var flagArgsSeparated []string
+	for _, flagArg := range flagArgs {
+		if strings.HasPrefix(flagArg, "-") && strings.HasPrefix(flagArg, "--") == false && len(flagArg) > 2 {
+			if !allCharsFlags(flagArg[1:]) {
+				flagArgsSeparated = append(flagArgsSeparated, flagArg)
+				continue
+			}
+			for _, flagChar := range flagArg[1:] {
+				flagArgsSeparated = append(flagArgsSeparated, "-"+string(flagChar))
+			}
+		} else {
+			flagArgsSeparated = append(flagArgsSeparated, flagArg)
+		}
+	}
+	return flagArgsSeparated
+}
+
+// Names returns the names including short names and aliases.
+func (c Command) Names() []string {
+	names := []string{c.Name}
+
+	if c.ShortName != "" {
+		names = append(names, c.ShortName)
+	}
+
+	return append(names, c.Aliases...)
+}
+
+// HasName returns true if Command.Name or Command.ShortName matches given name
 func (c Command) HasName(name string) bool {
-	return c.Name == name || c.ShortName == name
+	for _, n := range c.Names() {
+		if n == name {
+			return true
+		}
+	}
+	return false
 }
 
 func (c Command) startApp(ctx *Context) error {
 	app := NewApp()
-
+	app.Metadata = ctx.App.Metadata
 	// set the name and usage
 	app.Name = fmt.Sprintf("%s %s", ctx.App.Name, c.Name)
-	if c.Description != "" {
+	if c.HelpName == "" {
-		app.Usage = c.Description
+		app.HelpName = c.HelpName
 	} else {
-		app.Usage = c.Usage
+		app.HelpName = app.Name
 	}
 
+	app.Usage = c.Usage
+	app.Description = c.Description
+	app.ArgsUsage = c.ArgsUsage
+
 	// set CommandNotFound
 	app.CommandNotFound = ctx.App.CommandNotFound
+	app.CustomAppHelpTemplate = c.CustomHelpTemplate
 
 	// set the flags and commands
 	app.Commands = c.Subcommands
 	app.Flags = c.Flags
 	app.HideHelp = c.HideHelp
 
+	app.Version = ctx.App.Version
+	app.HideVersion = ctx.App.HideVersion
+	app.Compiled = ctx.App.Compiled
+	app.Author = ctx.App.Author
+	app.Email = ctx.App.Email
+	app.Writer = ctx.App.Writer
+	app.ErrWriter = ctx.App.ErrWriter
+
+	app.categories = CommandCategories{}
+	for _, command := range c.Subcommands {
+		app.categories = app.categories.AddCommand(command.Category, command)
+	}
+
+	sort.Sort(app.categories)
+
 	// bash completion
 	app.EnableBashCompletion = ctx.App.EnableBashCompletion
 	if c.BashComplete != nil {
@@ -165,9 +394,19 @@ func (c Command) startApp(ctx *Context) error {
 	} else {
 		app.Action = helpSubcommand.Action
 	}
+	app.OnUsageError = c.OnUsageError
+
+	for index, cc := range app.Commands {
+		app.Commands[index].commandNamePath = []string{c.Name, cc.Name}
+	}
 
 	// set the writer to the original App's writer
 	app.Writer = ctx.App.Writer
 
 	return app.RunAsSubcommand(ctx)
 }
+
+// VisibleFlags returns a slice of the Flags with Hidden=false
+func (c Command) VisibleFlags() []Flag {
+	return visibleFlags(c.Flags)
+}

command_test.go

@@ -1,49 +1,363 @@
-package cli_test
+package cli
 
 import (
+	"errors"
 	"flag"
+	"fmt"
+	"io/ioutil"
+	"strings"
 	"testing"
-
-	"github.com/codegangsta/cli"
 )
 
-func TestCommandDoNotIgnoreFlags(t *testing.T) {
+func TestCommandFlagParsing(t *testing.T) {
-	app := cli.NewApp()
+	cases := []struct {
-	set := flag.NewFlagSet("test", 0)
+		testArgs               []string
-	test := []string{"blah", "blah", "-break"}
+		skipFlagParsing        bool
-	set.Parse(test)
+		skipArgReorder         bool
+		expectedErr            error
+		UseShortOptionHandling bool
+	}{
+		// Test normal "not ignoring flags" flow
+		{[]string{"test-cmd", "blah", "blah", "-break"}, false, false, errors.New("flag provided but not defined: -break"), false},
 
-	c := cli.NewContext(app, set, set)
+		// Test no arg reorder
+		{[]string{"test-cmd", "blah", "blah", "-break"}, false, true, nil, false},
+		{[]string{"test-cmd", "blah", "blah", "-break", "ls", "-l"}, false, true, nil, true},
+
+		{[]string{"test-cmd", "blah", "blah"}, true, false, nil, false},   // Test SkipFlagParsing without any args that look like flags
+		{[]string{"test-cmd", "blah", "-break"}, true, false, nil, false}, // Test SkipFlagParsing with random flag arg
+		{[]string{"test-cmd", "blah", "-help"}, true, false, nil, false},  // Test SkipFlagParsing with "special" help flag arg
+		{[]string{"test-cmd", "blah"}, false, false, nil, true},           // Test UseShortOptionHandling
 
-	command := cli.Command{
-		Name:        "test-cmd",
-		ShortName:   "tc",
-		Usage:       "this is for testing",
-		Description: "testing",
-		Action:      func(_ *cli.Context) {},
 	}
-	err := command.Run(c)
 
-	expect(t, err.Error(), "flag provided but not defined: -break")
+	for _, c := range cases {
+		app := NewApp()
+		app.Writer = ioutil.Discard
+		set := flag.NewFlagSet("test", 0)
+		set.Parse(c.testArgs)
+
+		context := NewContext(app, set, nil)
+
+		command := Command{
+			Name:                   "test-cmd",
+			Aliases:                []string{"tc"},
+			Usage:                  "this is for testing",
+			Description:            "testing",
+			Action:                 func(_ *Context) error { return nil },
+			SkipFlagParsing:        c.skipFlagParsing,
+			SkipArgReorder:         c.skipArgReorder,
+			UseShortOptionHandling: c.UseShortOptionHandling,
+		}
+
+		err := command.Run(context)
+
+		expect(t, err, c.expectedErr)
+		expect(t, []string(context.Args()), c.testArgs)
+	}
 }
 
-func TestCommandIgnoreFlags(t *testing.T) {
+func TestParseAndRunShortOpts(t *testing.T) {
-	app := cli.NewApp()
+	cases := []struct {
-	set := flag.NewFlagSet("test", 0)
+		testArgs               []string
-	test := []string{"blah", "blah"}
+		expectedErr            error
-	set.Parse(test)
+		expectedArgs           []string
-
+	}{
-	c := cli.NewContext(app, set, set)
+		{[]string{"foo", "test", "-a"}, nil, []string{}},
-
+		{[]string{"foo", "test", "-c", "arg1", "arg2"}, nil, []string{"arg1", "arg2"}},
-	command := cli.Command{
+		{[]string{"foo", "test", "-f"}, nil, []string{}},
-		Name:            "test-cmd",
+		{[]string{"foo", "test", "-ac", "--fgh"}, nil, []string{}},
-		ShortName:       "tc",
+		{[]string{"foo", "test", "-af"}, nil, []string{}},
-		Usage:           "this is for testing",
+		{[]string{"foo", "test", "-cf"}, nil, []string{}},
-		Description:     "testing",
+		{[]string{"foo", "test", "-acf"}, nil, []string{}},
-		Action:          func(_ *cli.Context) {},
+		{[]string{"foo", "test", "-invalid"}, errors.New("flag provided but not defined: -invalid"), []string{}},
-		SkipFlagParsing: true,
+		{[]string{"foo", "test", "-acf", "arg1", "-invalid"}, nil, []string{"arg1" ,"-invalid"}},
 	}
-	err := command.Run(c)
 
-	expect(t, err, nil)
+	var args []string
+	cmd := Command{
+		Name:                   "test",
+		Usage:                  "this is for testing",
+		Description:            "testing",
+		Action:                 func(c *Context) error {
+						args = c.Args()
+						return nil
+					},
+		SkipArgReorder:         true,
+		UseShortOptionHandling: true,
+		Flags: []Flag{
+			BoolFlag{Name: "abc, a"},
+			BoolFlag{Name: "cde, c"},
+			BoolFlag{Name: "fgh, f"},
+		},
+	}
+
+	for _, c := range cases {
+		app := NewApp()
+		app.Commands = []Command{cmd}
+
+		err := app.Run(c.testArgs)
+
+		expect(t, err, c.expectedErr)
+		expect(t, args, c.expectedArgs)
+	}
+}
+
+func TestCommand_Run_DoesNotOverwriteErrorFromBefore(t *testing.T) {
+	app := NewApp()
+	app.Commands = []Command{
+		{
+			Name: "bar",
+			Before: func(c *Context) error {
+				return fmt.Errorf("before error")
+			},
+			After: func(c *Context) error {
+				return fmt.Errorf("after error")
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar"})
+	if err == nil {
+		t.Fatalf("expected to receive error from Run, got none")
+	}
+
+	if !strings.Contains(err.Error(), "before error") {
+		t.Errorf("expected text of error from Before method, but got none in \"%v\"", err)
+	}
+	if !strings.Contains(err.Error(), "after error") {
+		t.Errorf("expected text of error from After method, but got none in \"%v\"", err)
+	}
+}
+
+func TestCommand_Run_BeforeSavesMetadata(t *testing.T) {
+	var receivedMsgFromAction string
+	var receivedMsgFromAfter string
+
+	app := NewApp()
+	app.Commands = []Command{
+		{
+			Name: "bar",
+			Before: func(c *Context) error {
+				c.App.Metadata["msg"] = "hello world"
+				return nil
+			},
+			Action: func(c *Context) error {
+				msg, ok := c.App.Metadata["msg"]
+				if !ok {
+					return errors.New("msg not found")
+				}
+				receivedMsgFromAction = msg.(string)
+				return nil
+			},
+			After: func(c *Context) error {
+				msg, ok := c.App.Metadata["msg"]
+				if !ok {
+					return errors.New("msg not found")
+				}
+				receivedMsgFromAfter = msg.(string)
+				return nil
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar"})
+	if err != nil {
+		t.Fatalf("expected no error from Run, got %s", err)
+	}
+
+	expectedMsg := "hello world"
+
+	if receivedMsgFromAction != expectedMsg {
+		t.Fatalf("expected msg from Action to match. Given: %q\nExpected: %q",
+			receivedMsgFromAction, expectedMsg)
+	}
+	if receivedMsgFromAfter != expectedMsg {
+		t.Fatalf("expected msg from After to match. Given: %q\nExpected: %q",
+			receivedMsgFromAction, expectedMsg)
+	}
+}
+
+func TestCommand_OnUsageError_hasCommandContext(t *testing.T) {
+	app := NewApp()
+	app.Commands = []Command{
+		{
+			Name: "bar",
+			Flags: []Flag{
+				IntFlag{Name: "flag"},
+			},
+			OnUsageError: func(c *Context, err error, _ bool) error {
+				return fmt.Errorf("intercepted in %s: %s", c.Command.Name, err.Error())
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar", "--flag=wrong"})
+	if err == nil {
+		t.Fatalf("expected to receive error from Run, got none")
+	}
+
+	if !strings.HasPrefix(err.Error(), "intercepted in bar") {
+		t.Errorf("Expect an intercepted error, but got \"%v\"", err)
+	}
+}
+
+func TestCommand_OnUsageError_WithWrongFlagValue(t *testing.T) {
+	app := NewApp()
+	app.Commands = []Command{
+		{
+			Name: "bar",
+			Flags: []Flag{
+				IntFlag{Name: "flag"},
+			},
+			OnUsageError: func(c *Context, err error, _ bool) error {
+				if !strings.HasPrefix(err.Error(), "invalid value \"wrong\"") {
+					t.Errorf("Expect an invalid value error, but got \"%v\"", err)
+				}
+				return errors.New("intercepted: " + err.Error())
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar", "--flag=wrong"})
+	if err == nil {
+		t.Fatalf("expected to receive error from Run, got none")
+	}
+
+	if !strings.HasPrefix(err.Error(), "intercepted: invalid value") {
+		t.Errorf("Expect an intercepted error, but got \"%v\"", err)
+	}
+}
+
+func TestCommand_OnUsageError_WithSubcommand(t *testing.T) {
+	app := NewApp()
+	app.Commands = []Command{
+		{
+			Name: "bar",
+			Subcommands: []Command{
+				{
+					Name: "baz",
+				},
+			},
+			Flags: []Flag{
+				IntFlag{Name: "flag"},
+			},
+			OnUsageError: func(c *Context, err error, _ bool) error {
+				if !strings.HasPrefix(err.Error(), "invalid value \"wrong\"") {
+					t.Errorf("Expect an invalid value error, but got \"%v\"", err)
+				}
+				return errors.New("intercepted: " + err.Error())
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar", "--flag=wrong"})
+	if err == nil {
+		t.Fatalf("expected to receive error from Run, got none")
+	}
+
+	if !strings.HasPrefix(err.Error(), "intercepted: invalid value") {
+		t.Errorf("Expect an intercepted error, but got \"%v\"", err)
+	}
+}
+
+func TestCommand_Run_SubcommandsCanUseErrWriter(t *testing.T) {
+	app := NewApp()
+	app.ErrWriter = ioutil.Discard
+	app.Commands = []Command{
+		{
+			Name:  "bar",
+			Usage: "this is for testing",
+			Subcommands: []Command{
+				{
+					Name:  "baz",
+					Usage: "this is for testing",
+					Action: func(c *Context) error {
+						if c.App.ErrWriter != ioutil.Discard {
+							return fmt.Errorf("ErrWriter not passed")
+						}
+
+						return nil
+					},
+				},
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar", "baz"})
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestCommandFlagReordering(t *testing.T) {
+	cases := []struct {
+		testArgs      []string
+		expectedValue string
+		expectedArgs  []string
+		expectedErr   error
+	}{
+		{[]string{"some-exec", "some-command", "some-arg", "--flag", "foo"}, "foo", []string{"some-arg"}, nil},
+		{[]string{"some-exec", "some-command", "some-arg", "--flag=foo"}, "foo", []string{"some-arg"}, nil},
+		{[]string{"some-exec", "some-command", "--flag=foo", "some-arg"}, "foo", []string{"some-arg"}, nil},
+	}
+
+	for _, c := range cases {
+		value := ""
+		args := []string{}
+		app := &App{
+			Commands: []Command{
+				{
+					Name: "some-command",
+					Flags: []Flag{
+						StringFlag{Name: "flag"},
+					},
+					Action: func(c *Context) {
+						fmt.Printf("%+v\n", c.String("flag"))
+						value = c.String("flag")
+						args = c.Args()
+					},
+				},
+			},
+		}
+
+		err := app.Run(c.testArgs)
+		expect(t, err, c.expectedErr)
+		expect(t, value, c.expectedValue)
+		expect(t, args, c.expectedArgs)
+	}
+}
+
+func TestCommandSkipFlagParsing(t *testing.T) {
+	cases := []struct {
+		testArgs     []string
+		expectedArgs []string
+		expectedErr  error
+	}{
+		{[]string{"some-exec", "some-command", "some-arg", "--flag", "foo"}, []string{"some-arg", "--flag", "foo"}, nil},
+		{[]string{"some-exec", "some-command", "some-arg", "--flag=foo"}, []string{"some-arg", "--flag=foo"}, nil},
+	}
+
+	for _, c := range cases {
+		args := []string{}
+		app := &App{
+			Commands: []Command{
+				{
+					SkipFlagParsing: true,
+					Name:            "some-command",
+					Flags: []Flag{
+						StringFlag{Name: "flag"},
+					},
+					Action: func(c *Context) {
+						fmt.Printf("%+v\n", c.String("flag"))
+						args = c.Args()
+					},
+				},
+			},
+		}
+
+		err := app.Run(c.testArgs)
+		expect(t, err, c.expectedErr)
+		expect(t, args, c.expectedArgs)
+	}
 }

context.go

@@ -4,9 +4,10 @@ import (
 	"errors"
 	"flag"
 	"fmt"
-	"strconv"
+	"os"
+	"reflect"
 	"strings"
-	"time"
+	"syscall"
 )
 
 // Context is a type that is passed through to
@@ -14,125 +15,132 @@ import (
 // can be used to retrieve context-specific Args and
 // parsed command-line options.
 type Context struct {
-	App            *App
+	App           *App
-	Command        Command
+	Command       Command
-	flagSet        *flag.FlagSet
+	shellComplete bool
-	globalSet      *flag.FlagSet
+	flagSet       *flag.FlagSet
-	setFlags       map[string]bool
+	setFlags      map[string]bool
-	globalSetFlags map[string]bool
+	parentContext *Context
 }
 
-// Creates a new context. For use in when invoking an App or Command action.
+// NewContext creates a new context. For use in when invoking an App or Command action.
-func NewContext(app *App, set *flag.FlagSet, globalSet *flag.FlagSet) *Context {
+func NewContext(app *App, set *flag.FlagSet, parentCtx *Context) *Context {
-	return &Context{App: app, flagSet: set, globalSet: globalSet}
+	c := &Context{App: app, flagSet: set, parentContext: parentCtx}
+
+	if parentCtx != nil {
+		c.shellComplete = parentCtx.shellComplete
+	}
+
+	return c
 }
 
-// Looks up the value of a local int flag, returns 0 if no int flag exists
+// NumFlags returns the number of flags set
-func (c *Context) Int(name string) int {
+func (c *Context) NumFlags() int {
-	return lookupInt(name, c.flagSet)
+	return c.flagSet.NFlag()
 }
 
-// Looks up the value of a local time.Duration flag, returns 0 if no time.Duration flag exists
+// Set sets a context flag to a value.
-func (c *Context) Duration(name string) time.Duration {
+func (c *Context) Set(name, value string) error {
-	return lookupDuration(name, c.flagSet)
+	c.setFlags = nil
+	return c.flagSet.Set(name, value)
 }
 
-// Looks up the value of a local float64 flag, returns 0 if no float64 flag exists
+// GlobalSet sets a context flag to a value on the global flagset
-func (c *Context) Float64(name string) float64 {
+func (c *Context) GlobalSet(name, value string) error {
-	return lookupFloat64(name, c.flagSet)
+	globalContext(c).setFlags = nil
+	return globalContext(c).flagSet.Set(name, value)
 }
 
-// Looks up the value of a local bool flag, returns false if no bool flag exists
+// IsSet determines if the flag was actually set
-func (c *Context) Bool(name string) bool {
-	return lookupBool(name, c.flagSet)
-}
-
-// Looks up the value of a local boolT flag, returns false if no bool flag exists
-func (c *Context) BoolT(name string) bool {
-	return lookupBoolT(name, c.flagSet)
-}
-
-// Looks up the value of a local string flag, returns "" if no string flag exists
-func (c *Context) String(name string) string {
-	return lookupString(name, c.flagSet)
-}
-
-// Looks up the value of a local string slice flag, returns nil if no string slice flag exists
-func (c *Context) StringSlice(name string) []string {
-	return lookupStringSlice(name, c.flagSet)
-}
-
-// Looks up the value of a local int slice flag, returns nil if no int slice flag exists
-func (c *Context) IntSlice(name string) []int {
-	return lookupIntSlice(name, c.flagSet)
-}
-
-// Looks up the value of a local generic flag, returns nil if no generic flag exists
-func (c *Context) Generic(name string) interface{} {
-	return lookupGeneric(name, c.flagSet)
-}
-
-// Looks up the value of a global int flag, returns 0 if no int flag exists
-func (c *Context) GlobalInt(name string) int {
-	return lookupInt(name, c.globalSet)
-}
-
-// Looks up the value of a global time.Duration flag, returns 0 if no time.Duration flag exists
-func (c *Context) GlobalDuration(name string) time.Duration {
-	return lookupDuration(name, c.globalSet)
-}
-
-// Looks up the value of a global bool flag, returns false if no bool flag exists
-func (c *Context) GlobalBool(name string) bool {
-	return lookupBool(name, c.globalSet)
-}
-
-// Looks up the value of a global string flag, returns "" if no string flag exists
-func (c *Context) GlobalString(name string) string {
-	return lookupString(name, c.globalSet)
-}
-
-// Looks up the value of a global string slice flag, returns nil if no string slice flag exists
-func (c *Context) GlobalStringSlice(name string) []string {
-	return lookupStringSlice(name, c.globalSet)
-}
-
-// Looks up the value of a global int slice flag, returns nil if no int slice flag exists
-func (c *Context) GlobalIntSlice(name string) []int {
-	return lookupIntSlice(name, c.globalSet)
-}
-
-// Looks up the value of a global generic flag, returns nil if no generic flag exists
-func (c *Context) GlobalGeneric(name string) interface{} {
-	return lookupGeneric(name, c.globalSet)
-}
-
-// Determines if the flag was actually set
 func (c *Context) IsSet(name string) bool {
 	if c.setFlags == nil {
 		c.setFlags = make(map[string]bool)
+
 		c.flagSet.Visit(func(f *flag.Flag) {
 			c.setFlags[f.Name] = true
 		})
-	}
-	return c.setFlags[name] == true
-}
 
-// Determines if the global flag was actually set
+		c.flagSet.VisitAll(func(f *flag.Flag) {
-func (c *Context) GlobalIsSet(name string) bool {
+			if _, ok := c.setFlags[f.Name]; ok {
-	if c.globalSetFlags == nil {
+				return
-		c.globalSetFlags = make(map[string]bool)
+			}
-		c.globalSet.Visit(func(f *flag.Flag) {
+			c.setFlags[f.Name] = false
-			c.globalSetFlags[f.Name] = true
 		})
+
+		// XXX hack to support IsSet for flags with EnvVar
+		//
+		// There isn't an easy way to do this with the current implementation since
+		// whether a flag was set via an environment variable is very difficult to
+		// determine here. Instead, we intend to introduce a backwards incompatible
+		// change in version 2 to add `IsSet` to the Flag interface to push the
+		// responsibility closer to where the information required to determine
+		// whether a flag is set by non-standard means such as environment
+		// variables is available.
+		//
+		// See https://github.com/urfave/cli/issues/294 for additional discussion
+		flags := c.Command.Flags
+		if c.Command.Name == "" { // cannot == Command{} since it contains slice types
+			if c.App != nil {
+				flags = c.App.Flags
+			}
+		}
+		for _, f := range flags {
+			eachName(f.GetName(), func(name string) {
+				if isSet, ok := c.setFlags[name]; isSet || !ok {
+					return
+				}
+
+				val := reflect.ValueOf(f)
+				if val.Kind() == reflect.Ptr {
+					val = val.Elem()
+				}
+
+				filePathValue := val.FieldByName("FilePath")
+				if filePathValue.IsValid() {
+					eachName(filePathValue.String(), func(filePath string) {
+						if _, err := os.Stat(filePath); err == nil {
+							c.setFlags[name] = true
+							return
+						}
+					})
+				}
+
+				envVarValue := val.FieldByName("EnvVar")
+				if envVarValue.IsValid() {
+					eachName(envVarValue.String(), func(envVar string) {
+						envVar = strings.TrimSpace(envVar)
+						if _, ok := syscall.Getenv(envVar); ok {
+							c.setFlags[name] = true
+							return
+						}
+					})
+				}
+			})
+		}
 	}
-	return c.globalSetFlags[name] == true
+
+	return c.setFlags[name]
 }
 
-// Returns a slice of flag names used in this context.
+// GlobalIsSet determines if the global flag was actually set
+func (c *Context) GlobalIsSet(name string) bool {
+	ctx := c
+	if ctx.parentContext != nil {
+		ctx = ctx.parentContext
+	}
+
+	for ; ctx != nil; ctx = ctx.parentContext {
+		if ctx.IsSet(name) {
+			return true
+		}
+	}
+	return false
+}
+
+// FlagNames returns a slice of flag names used in this context.
 func (c *Context) FlagNames() (names []string) {
 	for _, flag := range c.Command.Flags {
-		name := strings.Split(flag.getName(), ",")[0]
+		name := strings.Split(flag.GetName(), ",")[0]
 		if name == "help" {
 			continue
 		}
@@ -141,10 +149,10 @@ func (c *Context) FlagNames() (names []string) {
 	return
 }
 
-// Returns a slice of global flag names used by the app.
+// GlobalFlagNames returns a slice of global flag names used by the app.
 func (c *Context) GlobalFlagNames() (names []string) {
 	for _, flag := range c.App.Flags {
-		name := strings.Split(flag.getName(), ",")[0]
+		name := strings.Split(flag.GetName(), ",")[0]
 		if name == "help" || name == "version" {
 			continue
 		}
@@ -153,15 +161,31 @@ func (c *Context) GlobalFlagNames() (names []string) {
 	return
 }
 
+// Parent returns the parent context, if any
+func (c *Context) Parent() *Context {
+	return c.parentContext
+}
+
+// value returns the value of the flag coressponding to `name`
+func (c *Context) value(name string) interface{} {
+	return c.flagSet.Lookup(name).Value.(flag.Getter).Get()
+}
+
+// Args contains apps console arguments
 type Args []string
 
-// Returns the command line arguments associated with the context.
+// Args returns the command line arguments associated with the context.
 func (c *Context) Args() Args {
 	args := Args(c.flagSet.Args())
 	return args
 }
 
-// Returns the nth argument, or else a blank string
+// NArg returns the number of the command line arguments.
+func (c *Context) NArg() int {
+	return len(c.Args())
+}
+
+// Get returns the nth argument, or else a blank string
 func (a Args) Get(n int) string {
 	if len(a) > n {
 		return a[n]
@@ -169,12 +193,12 @@ func (a Args) Get(n int) string {
 	return ""
 }
 
-// Returns the first argument, or else a blank string
+// First returns the first argument, or else a blank string
 func (a Args) First() string {
 	return a.Get(0)
 }
 
-// Return the rest of the arguments (not the first one)
+// Tail returns the rest of the arguments (not the first one)
 // or else an empty string slice
 func (a Args) Tail() []string {
 	if len(a) >= 2 {
@@ -183,12 +207,12 @@ func (a Args) Tail() []string {
 	return []string{}
 }
 
-// Checks if there are any arguments present
+// Present checks if there are any arguments present
 func (a Args) Present() bool {
 	return len(a) != 0
 }
 
-// Swaps arguments at the given indexes
+// Swap swaps arguments at the given indexes
 func (a Args) Swap(from, to int) error {
 	if from >= len(a) || to >= len(a) {
 		return errors.New("index out of range")
@@ -197,107 +221,31 @@ func (a Args) Swap(from, to int) error {
 	return nil
 }
 
-func lookupInt(name string, set *flag.FlagSet) int {
+func globalContext(ctx *Context) *Context {
-	f := set.Lookup(name)
+	if ctx == nil {
-	if f != nil {
+		return nil
-		val, err := strconv.Atoi(f.Value.String())
+	}
-		if err != nil {
+
-			return 0
+	for {
+		if ctx.parentContext == nil {
+			return ctx
 		}
-		return val
+		ctx = ctx.parentContext
 	}
-
-	return 0
 }
 
-func lookupDuration(name string, set *flag.FlagSet) time.Duration {
+func lookupGlobalFlagSet(name string, ctx *Context) *flag.FlagSet {
-	f := set.Lookup(name)
+	if ctx.parentContext != nil {
-	if f != nil {
+		ctx = ctx.parentContext
-		val, err := time.ParseDuration(f.Value.String())
+	}
-		if err == nil {
+	for ; ctx != nil; ctx = ctx.parentContext {
-			return val
+		if f := ctx.flagSet.Lookup(name); f != nil {
+			return ctx.flagSet
 		}
 	}
-
-	return 0
-}
-
-func lookupFloat64(name string, set *flag.FlagSet) float64 {
-	f := set.Lookup(name)
-	if f != nil {
-		val, err := strconv.ParseFloat(f.Value.String(), 64)
-		if err != nil {
-			return 0
-		}
-		return val
-	}
-
-	return 0
-}
-
-func lookupString(name string, set *flag.FlagSet) string {
-	f := set.Lookup(name)
-	if f != nil {
-		return f.Value.String()
-	}
-
-	return ""
-}
-
-func lookupStringSlice(name string, set *flag.FlagSet) []string {
-	f := set.Lookup(name)
-	if f != nil {
-		return (f.Value.(*StringSlice)).Value()
-
-	}
-
-	return nil
-}
-
-func lookupIntSlice(name string, set *flag.FlagSet) []int {
-	f := set.Lookup(name)
-	if f != nil {
-		return (f.Value.(*IntSlice)).Value()
-
-	}
-
-	return nil
-}
-
-func lookupGeneric(name string, set *flag.FlagSet) interface{} {
-	f := set.Lookup(name)
-	if f != nil {
-		return f.Value
-	}
 	return nil
 }
 
-func lookupBool(name string, set *flag.FlagSet) bool {
-	f := set.Lookup(name)
-	if f != nil {
-		val, err := strconv.ParseBool(f.Value.String())
-		if err != nil {
-			return false
-		}
-		return val
-	}
-
-	return false
-}
-
-func lookupBoolT(name string, set *flag.FlagSet) bool {
-	f := set.Lookup(name)
-	if f != nil {
-		val, err := strconv.ParseBool(f.Value.String())
-		if err != nil {
-			return true
-		}
-		return val
-	}
-
-	return false
-}
-
 func copyFlag(name string, ff *flag.Flag, set *flag.FlagSet) {
 	switch ff.Value.(type) {
 	case *StringSlice:
@@ -312,7 +260,7 @@ func normalizeFlags(flags []Flag, set *flag.FlagSet) error {
 		visited[f.Name] = true
 	})
 	for _, f := range flags {
-		parts := strings.Split(f.getName(), ",")
+		parts := strings.Split(f.GetName(), ",")
 		if len(parts) == 1 {
 			continue
 		}

context_test.go

@@ -1,77 +1,178 @@
-package cli_test
+package cli
 
 import (
 	"flag"
+	"os"
 	"testing"
 	"time"
-
-	"github.com/codegangsta/cli"
 )
 
 func TestNewContext(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Int("myflag", 12, "doc")
+	set.Int64("myflagInt64", int64(12), "doc")
+	set.Uint("myflagUint", uint(93), "doc")
+	set.Uint64("myflagUint64", uint64(93), "doc")
+	set.Float64("myflag64", float64(17), "doc")
 	globalSet := flag.NewFlagSet("test", 0)
 	globalSet.Int("myflag", 42, "doc")
-	command := cli.Command{Name: "mycommand"}
+	globalSet.Int64("myflagInt64", int64(42), "doc")
-	c := cli.NewContext(nil, set, globalSet)
+	globalSet.Uint("myflagUint", uint(33), "doc")
+	globalSet.Uint64("myflagUint64", uint64(33), "doc")
+	globalSet.Float64("myflag64", float64(47), "doc")
+	globalCtx := NewContext(nil, globalSet, nil)
+	command := Command{Name: "mycommand"}
+	c := NewContext(nil, set, globalCtx)
 	c.Command = command
 	expect(t, c.Int("myflag"), 12)
+	expect(t, c.Int64("myflagInt64"), int64(12))
+	expect(t, c.Uint("myflagUint"), uint(93))
+	expect(t, c.Uint64("myflagUint64"), uint64(93))
+	expect(t, c.Float64("myflag64"), float64(17))
 	expect(t, c.GlobalInt("myflag"), 42)
+	expect(t, c.GlobalInt64("myflagInt64"), int64(42))
+	expect(t, c.GlobalUint("myflagUint"), uint(33))
+	expect(t, c.GlobalUint64("myflagUint64"), uint64(33))
+	expect(t, c.GlobalFloat64("myflag64"), float64(47))
 	expect(t, c.Command.Name, "mycommand")
 }
 
 func TestContext_Int(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Int("myflag", 12, "doc")
-	c := cli.NewContext(nil, set, set)
+	c := NewContext(nil, set, nil)
 	expect(t, c.Int("myflag"), 12)
 }
 
+func TestContext_Int64(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Int64("myflagInt64", 12, "doc")
+	c := NewContext(nil, set, nil)
+	expect(t, c.Int64("myflagInt64"), int64(12))
+}
+
+func TestContext_Uint(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Uint("myflagUint", uint(13), "doc")
+	c := NewContext(nil, set, nil)
+	expect(t, c.Uint("myflagUint"), uint(13))
+}
+
+func TestContext_Uint64(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Uint64("myflagUint64", uint64(9), "doc")
+	c := NewContext(nil, set, nil)
+	expect(t, c.Uint64("myflagUint64"), uint64(9))
+}
+
+func TestContext_GlobalInt(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Int("myflag", 12, "doc")
+	c := NewContext(nil, set, nil)
+	expect(t, c.GlobalInt("myflag"), 12)
+	expect(t, c.GlobalInt("nope"), 0)
+}
+
+func TestContext_GlobalInt64(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Int64("myflagInt64", 12, "doc")
+	c := NewContext(nil, set, nil)
+	expect(t, c.GlobalInt64("myflagInt64"), int64(12))
+	expect(t, c.GlobalInt64("nope"), int64(0))
+}
+
+func TestContext_Float64(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Float64("myflag", float64(17), "doc")
+	c := NewContext(nil, set, nil)
+	expect(t, c.Float64("myflag"), float64(17))
+}
+
+func TestContext_GlobalFloat64(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Float64("myflag", float64(17), "doc")
+	c := NewContext(nil, set, nil)
+	expect(t, c.GlobalFloat64("myflag"), float64(17))
+	expect(t, c.GlobalFloat64("nope"), float64(0))
+}
+
 func TestContext_Duration(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Duration("myflag", time.Duration(12*time.Second), "doc")
-	c := cli.NewContext(nil, set, set)
+	c := NewContext(nil, set, nil)
 	expect(t, c.Duration("myflag"), time.Duration(12*time.Second))
 }
 
 func TestContext_String(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.String("myflag", "hello world", "doc")
-	c := cli.NewContext(nil, set, set)
+	c := NewContext(nil, set, nil)
 	expect(t, c.String("myflag"), "hello world")
 }
 
 func TestContext_Bool(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Bool("myflag", false, "doc")
-	c := cli.NewContext(nil, set, set)
+	c := NewContext(nil, set, nil)
 	expect(t, c.Bool("myflag"), false)
 }
 
 func TestContext_BoolT(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Bool("myflag", true, "doc")
-	c := cli.NewContext(nil, set, set)
+	c := NewContext(nil, set, nil)
 	expect(t, c.BoolT("myflag"), true)
 }
 
+func TestContext_GlobalBool(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+
+	globalSet := flag.NewFlagSet("test-global", 0)
+	globalSet.Bool("myflag", false, "doc")
+	globalCtx := NewContext(nil, globalSet, nil)
+
+	c := NewContext(nil, set, globalCtx)
+	expect(t, c.GlobalBool("myflag"), false)
+	expect(t, c.GlobalBool("nope"), false)
+}
+
+func TestContext_GlobalBoolT(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+
+	globalSet := flag.NewFlagSet("test-global", 0)
+	globalSet.Bool("myflag", true, "doc")
+	globalCtx := NewContext(nil, globalSet, nil)
+
+	c := NewContext(nil, set, globalCtx)
+	expect(t, c.GlobalBoolT("myflag"), true)
+	expect(t, c.GlobalBoolT("nope"), false)
+}
+
 func TestContext_Args(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Bool("myflag", false, "doc")
-	c := cli.NewContext(nil, set, set)
+	c := NewContext(nil, set, nil)
 	set.Parse([]string{"--myflag", "bat", "baz"})
 	expect(t, len(c.Args()), 2)
 	expect(t, c.Bool("myflag"), true)
 }
 
+func TestContext_NArg(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Bool("myflag", false, "doc")
+	c := NewContext(nil, set, nil)
+	set.Parse([]string{"--myflag", "bat", "baz"})
+	expect(t, c.NArg(), 2)
+}
+
 func TestContext_IsSet(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Bool("myflag", false, "doc")
 	set.String("otherflag", "hello world", "doc")
 	globalSet := flag.NewFlagSet("test", 0)
 	globalSet.Bool("myflagGlobal", true, "doc")
-	c := cli.NewContext(nil, set, globalSet)
+	globalCtx := NewContext(nil, globalSet, nil)
+	c := NewContext(nil, set, globalCtx)
 	set.Parse([]string{"--myflag", "bat", "baz"})
 	globalSet.Parse([]string{"--myflagGlobal", "bat", "baz"})
 	expect(t, c.IsSet("myflag"), true)
@@ -80,6 +181,52 @@ func TestContext_IsSet(t *testing.T) {
 	expect(t, c.IsSet("myflagGlobal"), false)
 }
 
+// XXX Corresponds to hack in context.IsSet for flags with EnvVar field
+// Should be moved to `flag_test` in v2
+func TestContext_IsSet_fromEnv(t *testing.T) {
+	var (
+		timeoutIsSet, tIsSet    bool
+		noEnvVarIsSet, nIsSet   bool
+		passwordIsSet, pIsSet   bool
+		unparsableIsSet, uIsSet bool
+	)
+
+	clearenv()
+	os.Setenv("APP_TIMEOUT_SECONDS", "15.5")
+	os.Setenv("APP_PASSWORD", "")
+	a := App{
+		Flags: []Flag{
+			Float64Flag{Name: "timeout, t", EnvVar: "APP_TIMEOUT_SECONDS"},
+			StringFlag{Name: "password, p", EnvVar: "APP_PASSWORD"},
+			Float64Flag{Name: "unparsable, u", EnvVar: "APP_UNPARSABLE"},
+			Float64Flag{Name: "no-env-var, n"},
+		},
+		Action: func(ctx *Context) error {
+			timeoutIsSet = ctx.IsSet("timeout")
+			tIsSet = ctx.IsSet("t")
+			passwordIsSet = ctx.IsSet("password")
+			pIsSet = ctx.IsSet("p")
+			unparsableIsSet = ctx.IsSet("unparsable")
+			uIsSet = ctx.IsSet("u")
+			noEnvVarIsSet = ctx.IsSet("no-env-var")
+			nIsSet = ctx.IsSet("n")
+			return nil
+		},
+	}
+	a.Run([]string{"run"})
+	expect(t, timeoutIsSet, true)
+	expect(t, tIsSet, true)
+	expect(t, passwordIsSet, true)
+	expect(t, pIsSet, true)
+	expect(t, noEnvVarIsSet, false)
+	expect(t, nIsSet, false)
+
+	os.Setenv("APP_UNPARSABLE", "foobar")
+	a.Run([]string{"run"})
+	expect(t, unparsableIsSet, false)
+	expect(t, uIsSet, false)
+}
+
 func TestContext_GlobalIsSet(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.Bool("myflag", false, "doc")
@@ -87,7 +234,8 @@ func TestContext_GlobalIsSet(t *testing.T) {
 	globalSet := flag.NewFlagSet("test", 0)
 	globalSet.Bool("myflagGlobal", true, "doc")
 	globalSet.Bool("myflagGlobalUnset", true, "doc")
-	c := cli.NewContext(nil, set, globalSet)
+	globalCtx := NewContext(nil, globalSet, nil)
+	c := NewContext(nil, set, globalCtx)
 	set.Parse([]string{"--myflag", "bat", "baz"})
 	globalSet.Parse([]string{"--myflagGlobal", "bat", "baz"})
 	expect(t, c.GlobalIsSet("myflag"), false)
@@ -97,3 +245,159 @@ func TestContext_GlobalIsSet(t *testing.T) {
 	expect(t, c.GlobalIsSet("myflagGlobalUnset"), false)
 	expect(t, c.GlobalIsSet("bogusGlobal"), false)
 }
+
+// XXX Corresponds to hack in context.IsSet for flags with EnvVar field
+// Should be moved to `flag_test` in v2
+func TestContext_GlobalIsSet_fromEnv(t *testing.T) {
+	var (
+		timeoutIsSet, tIsSet    bool
+		noEnvVarIsSet, nIsSet   bool
+		passwordIsSet, pIsSet   bool
+		unparsableIsSet, uIsSet bool
+	)
+
+	clearenv()
+	os.Setenv("APP_TIMEOUT_SECONDS", "15.5")
+	os.Setenv("APP_PASSWORD", "")
+	a := App{
+		Flags: []Flag{
+			Float64Flag{Name: "timeout, t", EnvVar: "APP_TIMEOUT_SECONDS"},
+			StringFlag{Name: "password, p", EnvVar: "APP_PASSWORD"},
+			Float64Flag{Name: "no-env-var, n"},
+			Float64Flag{Name: "unparsable, u", EnvVar: "APP_UNPARSABLE"},
+		},
+		Commands: []Command{
+			{
+				Name: "hello",
+				Action: func(ctx *Context) error {
+					timeoutIsSet = ctx.GlobalIsSet("timeout")
+					tIsSet = ctx.GlobalIsSet("t")
+					passwordIsSet = ctx.GlobalIsSet("password")
+					pIsSet = ctx.GlobalIsSet("p")
+					unparsableIsSet = ctx.GlobalIsSet("unparsable")
+					uIsSet = ctx.GlobalIsSet("u")
+					noEnvVarIsSet = ctx.GlobalIsSet("no-env-var")
+					nIsSet = ctx.GlobalIsSet("n")
+					return nil
+				},
+			},
+		},
+	}
+	if err := a.Run([]string{"run", "hello"}); err != nil {
+		t.Logf("error running Run(): %+v", err)
+	}
+	expect(t, timeoutIsSet, true)
+	expect(t, tIsSet, true)
+	expect(t, passwordIsSet, true)
+	expect(t, pIsSet, true)
+	expect(t, noEnvVarIsSet, false)
+	expect(t, nIsSet, false)
+
+	os.Setenv("APP_UNPARSABLE", "foobar")
+	if err := a.Run([]string{"run"}); err != nil {
+		t.Logf("error running Run(): %+v", err)
+	}
+	expect(t, unparsableIsSet, false)
+	expect(t, uIsSet, false)
+}
+
+func TestContext_NumFlags(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Bool("myflag", false, "doc")
+	set.String("otherflag", "hello world", "doc")
+	globalSet := flag.NewFlagSet("test", 0)
+	globalSet.Bool("myflagGlobal", true, "doc")
+	globalCtx := NewContext(nil, globalSet, nil)
+	c := NewContext(nil, set, globalCtx)
+	set.Parse([]string{"--myflag", "--otherflag=foo"})
+	globalSet.Parse([]string{"--myflagGlobal"})
+	expect(t, c.NumFlags(), 2)
+}
+
+func TestContext_GlobalFlag(t *testing.T) {
+	var globalFlag string
+	var globalFlagSet bool
+	app := NewApp()
+	app.Flags = []Flag{
+		StringFlag{Name: "global, g", Usage: "global"},
+	}
+	app.Action = func(c *Context) error {
+		globalFlag = c.GlobalString("global")
+		globalFlagSet = c.GlobalIsSet("global")
+		return nil
+	}
+	app.Run([]string{"command", "-g", "foo"})
+	expect(t, globalFlag, "foo")
+	expect(t, globalFlagSet, true)
+
+}
+
+func TestContext_GlobalFlagsInSubcommands(t *testing.T) {
+	subcommandRun := false
+	parentFlag := false
+	app := NewApp()
+
+	app.Flags = []Flag{
+		BoolFlag{Name: "debug, d", Usage: "Enable debugging"},
+	}
+
+	app.Commands = []Command{
+		{
+			Name: "foo",
+			Flags: []Flag{
+				BoolFlag{Name: "parent, p", Usage: "Parent flag"},
+			},
+			Subcommands: []Command{
+				{
+					Name: "bar",
+					Action: func(c *Context) error {
+						if c.GlobalBool("debug") {
+							subcommandRun = true
+						}
+						if c.GlobalBool("parent") {
+							parentFlag = true
+						}
+						return nil
+					},
+				},
+			},
+		},
+	}
+
+	app.Run([]string{"command", "-d", "foo", "-p", "bar"})
+
+	expect(t, subcommandRun, true)
+	expect(t, parentFlag, true)
+}
+
+func TestContext_Set(t *testing.T) {
+	set := flag.NewFlagSet("test", 0)
+	set.Int("int", 5, "an int")
+	c := NewContext(nil, set, nil)
+
+	expect(t, c.IsSet("int"), false)
+	c.Set("int", "1")
+	expect(t, c.Int("int"), 1)
+	expect(t, c.IsSet("int"), true)
+}
+
+func TestContext_GlobalSet(t *testing.T) {
+	gSet := flag.NewFlagSet("test", 0)
+	gSet.Int("int", 5, "an int")
+
+	set := flag.NewFlagSet("sub", 0)
+	set.Int("int", 3, "an int")
+
+	pc := NewContext(nil, gSet, nil)
+	c := NewContext(nil, set, pc)
+
+	c.Set("int", "1")
+	expect(t, c.Int("int"), 1)
+	expect(t, c.GlobalInt("int"), 5)
+
+	expect(t, c.GlobalIsSet("int"), false)
+	c.GlobalSet("int", "1")
+	expect(t, c.Int("int"), 1)
+	expect(t, c.GlobalInt("int"), 1)
+	expect(t, c.GlobalIsSet("int"), true)
+}

errors.go

@@ -0,0 +1,115 @@
+package cli
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+// OsExiter is the function used when the app exits. If not set defaults to os.Exit.
+var OsExiter = os.Exit
+
+// ErrWriter is used to write errors to the user. This can be anything
+// implementing the io.Writer interface and defaults to os.Stderr.
+var ErrWriter io.Writer = os.Stderr
+
+// MultiError is an error that wraps multiple errors.
+type MultiError struct {
+	Errors []error
+}
+
+// NewMultiError creates a new MultiError. Pass in one or more errors.
+func NewMultiError(err ...error) MultiError {
+	return MultiError{Errors: err}
+}
+
+// Error implements the error interface.
+func (m MultiError) Error() string {
+	errs := make([]string, len(m.Errors))
+	for i, err := range m.Errors {
+		errs[i] = err.Error()
+	}
+
+	return strings.Join(errs, "\n")
+}
+
+type ErrorFormatter interface {
+	Format(s fmt.State, verb rune)
+}
+
+// ExitCoder is the interface checked by `App` and `Command` for a custom exit
+// code
+type ExitCoder interface {
+	error
+	ExitCode() int
+}
+
+// ExitError fulfills both the builtin `error` interface and `ExitCoder`
+type ExitError struct {
+	exitCode int
+	message  interface{}
+}
+
+// NewExitError makes a new *ExitError
+func NewExitError(message interface{}, exitCode int) *ExitError {
+	return &ExitError{
+		exitCode: exitCode,
+		message:  message,
+	}
+}
+
+// Error returns the string message, fulfilling the interface required by
+// `error`
+func (ee *ExitError) Error() string {
+	return fmt.Sprintf("%v", ee.message)
+}
+
+// ExitCode returns the exit code, fulfilling the interface required by
+// `ExitCoder`
+func (ee *ExitError) ExitCode() int {
+	return ee.exitCode
+}
+
+// HandleExitCoder checks if the error fulfills the ExitCoder interface, and if
+// so prints the error to stderr (if it is non-empty) and calls OsExiter with the
+// given exit code.  If the given error is a MultiError, then this func is
+// called on all members of the Errors slice and calls OsExiter with the last exit code.
+func HandleExitCoder(err error) {
+	if err == nil {
+		return
+	}
+
+	if exitErr, ok := err.(ExitCoder); ok {
+		if err.Error() != "" {
+			if _, ok := exitErr.(ErrorFormatter); ok {
+				fmt.Fprintf(ErrWriter, "%+v\n", err)
+			} else {
+				fmt.Fprintln(ErrWriter, err)
+			}
+		}
+		OsExiter(exitErr.ExitCode())
+		return
+	}
+
+	if multiErr, ok := err.(MultiError); ok {
+		code := handleMultiError(multiErr)
+		OsExiter(code)
+		return
+	}
+}
+
+func handleMultiError(multiErr MultiError) int {
+	code := 1
+	for _, merr := range multiErr.Errors {
+		if multiErr2, ok := merr.(MultiError); ok {
+			code = handleMultiError(multiErr2)
+		} else {
+			fmt.Fprintln(ErrWriter, merr)
+			if exitErr, ok := merr.(ExitCoder); ok {
+				code = exitErr.ExitCode()
+			}
+		}
+	}
+	return code
+}

errors_test.go

@@ -0,0 +1,122 @@
+package cli
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"testing"
+)
+
+func TestHandleExitCoder_nil(t *testing.T) {
+	exitCode := 0
+	called := false
+
+	OsExiter = func(rc int) {
+		if !called {
+			exitCode = rc
+			called = true
+		}
+	}
+
+	defer func() { OsExiter = fakeOsExiter }()
+
+	HandleExitCoder(nil)
+
+	expect(t, exitCode, 0)
+	expect(t, called, false)
+}
+
+func TestHandleExitCoder_ExitCoder(t *testing.T) {
+	exitCode := 0
+	called := false
+
+	OsExiter = func(rc int) {
+		if !called {
+			exitCode = rc
+			called = true
+		}
+	}
+
+	defer func() { OsExiter = fakeOsExiter }()
+
+	HandleExitCoder(NewExitError("galactic perimeter breach", 9))
+
+	expect(t, exitCode, 9)
+	expect(t, called, true)
+}
+
+func TestHandleExitCoder_MultiErrorWithExitCoder(t *testing.T) {
+	exitCode := 0
+	called := false
+
+	OsExiter = func(rc int) {
+		if !called {
+			exitCode = rc
+			called = true
+		}
+	}
+
+	defer func() { OsExiter = fakeOsExiter }()
+
+	exitErr := NewExitError("galactic perimeter breach", 9)
+	exitErr2 := NewExitError("last ExitCoder", 11)
+	err := NewMultiError(errors.New("wowsa"), errors.New("egad"), exitErr, exitErr2)
+	HandleExitCoder(err)
+
+	expect(t, exitCode, 11)
+	expect(t, called, true)
+}
+
+// make a stub to not import pkg/errors
+type ErrorWithFormat struct {
+	error
+}
+
+func NewErrorWithFormat(m string) *ErrorWithFormat {
+	return &ErrorWithFormat{error: errors.New(m)}
+}
+
+func (f *ErrorWithFormat) Format(s fmt.State, verb rune) {
+	fmt.Fprintf(s, "This the format: %v", f.error)
+}
+
+func TestHandleExitCoder_ErrorWithFormat(t *testing.T) {
+	called := false
+
+	OsExiter = func(rc int) {
+		if !called {
+			called = true
+		}
+	}
+	ErrWriter = &bytes.Buffer{}
+
+	defer func() {
+		OsExiter = fakeOsExiter
+		ErrWriter = fakeErrWriter
+	}()
+
+	err := NewExitError(NewErrorWithFormat("I am formatted"), 1)
+	HandleExitCoder(err)
+
+	expect(t, called, true)
+	expect(t, ErrWriter.(*bytes.Buffer).String(), "This the format: I am formatted\n")
+}
+
+func TestHandleExitCoder_MultiErrorWithFormat(t *testing.T) {
+	called := false
+
+	OsExiter = func(rc int) {
+		if !called {
+			called = true
+		}
+	}
+	ErrWriter = &bytes.Buffer{}
+
+	defer func() { OsExiter = fakeOsExiter }()
+
+	err := NewMultiError(NewErrorWithFormat("err1"), NewErrorWithFormat("err2"))
+	HandleExitCoder(err)
+
+	expect(t, called, true)
+	expect(t, ErrWriter.(*bytes.Buffer).String(), "This the format: err1\nThis the format: err2\n")
+}

flag-types.json

@@ -0,0 +1,93 @@
+[
+  {
+    "name": "Bool",
+    "type": "bool",
+    "value": false,
+    "context_default": "false",
+    "parser": "strconv.ParseBool(f.Value.String())"
+  },
+  {
+    "name": "BoolT",
+    "type": "bool",
+    "value": false,
+    "doctail": " that is true by default",
+    "context_default": "false",
+    "parser": "strconv.ParseBool(f.Value.String())"
+  },
+  {
+    "name": "Duration",
+    "type": "time.Duration",
+    "doctail": " (see https://golang.org/pkg/time/#ParseDuration)",
+    "context_default": "0",
+    "parser": "time.ParseDuration(f.Value.String())"
+  },
+  {
+    "name": "Float64",
+    "type": "float64",
+    "context_default": "0",
+    "parser": "strconv.ParseFloat(f.Value.String(), 64)"
+  },
+  {
+    "name": "Generic",
+    "type": "Generic",
+    "dest": false,
+    "context_default": "nil",
+    "context_type": "interface{}"
+  },
+  {
+    "name": "Int64",
+    "type": "int64",
+    "context_default": "0",
+    "parser": "strconv.ParseInt(f.Value.String(), 0, 64)"
+  },
+  {
+    "name": "Int",
+    "type": "int",
+    "context_default": "0",
+    "parser": "strconv.ParseInt(f.Value.String(), 0, 64)",
+    "parser_cast": "int(parsed)"
+  },
+  {
+    "name": "IntSlice",
+    "type": "*IntSlice",
+    "dest": false,
+    "context_default": "nil",
+    "context_type": "[]int",
+    "parser": "(f.Value.(*IntSlice)).Value(), error(nil)"
+  },
+  {
+    "name": "Int64Slice",
+    "type": "*Int64Slice",
+    "dest": false,
+    "context_default": "nil",
+    "context_type": "[]int64",
+    "parser": "(f.Value.(*Int64Slice)).Value(), error(nil)"
+  },
+  {
+    "name": "String",
+    "type": "string",
+    "context_default": "\"\"",
+    "parser": "f.Value.String(), error(nil)"
+  },
+  {
+    "name": "StringSlice",
+    "type": "*StringSlice",
+    "dest": false,
+    "context_default": "nil",
+    "context_type": "[]string",
+    "parser": "(f.Value.(*StringSlice)).Value(), error(nil)"
+  },
+  {
+    "name": "Uint64",
+    "type": "uint64",
+    "context_default": "0",
+    "parser": "strconv.ParseUint(f.Value.String(), 0, 64)"
+  },
+  {
+    "name": "Uint",
+    "type": "uint",
+    "context_default": "0",
+    "parser": "strconv.ParseUint(f.Value.String(), 0, 64)",
+    "parser_cast": "uint(parsed)"
+  }
+]

flag.go

@@ -3,49 +3,102 @@ package cli
 import (
 	"flag"
 	"fmt"
-	"os"
+	"io/ioutil"
+	"reflect"
+	"runtime"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 )
 
-// This flag enables bash-completion for all commands and subcommands
+const defaultPlaceholder = "value"
-var BashCompletionFlag = BoolFlag{
+
-	Name: "generate-bash-completion",
+// BashCompletionFlag enables bash-completion for all commands and subcommands
+var BashCompletionFlag Flag = BoolFlag{
+	Name:   "generate-bash-completion",
+	Hidden: true,
 }
 
-// This flag prints the version for the application
+// VersionFlag prints the version for the application
-var VersionFlag = BoolFlag{
+var VersionFlag Flag = BoolFlag{
 	Name:  "version, v",
 	Usage: "print the version",
 }
 
-// This flag prints the help for all commands and subcommands
+// HelpFlag prints the help for all commands and subcommands
 // Set to the zero value (BoolFlag{}) to disable flag -- keeps subcommand
 // unless HideHelp is set to true)
-var HelpFlag = BoolFlag{
+var HelpFlag Flag = BoolFlag{
 	Name:  "help, h",
 	Usage: "show help",
 }
 
+// FlagStringer converts a flag definition to a string. This is used by help
+// to display a flag.
+var FlagStringer FlagStringFunc = stringifyFlag
+
+// FlagNamePrefixer converts a full flag name and its placeholder into the help
+// message flag prefix. This is used by the default FlagStringer.
+var FlagNamePrefixer FlagNamePrefixFunc = prefixedNames
+
+// FlagEnvHinter annotates flag help message with the environment variable
+// details. This is used by the default FlagStringer.
+var FlagEnvHinter FlagEnvHintFunc = withEnvHint
+
+// FlagFileHinter annotates flag help message with the environment variable
+// details. This is used by the default FlagStringer.
+var FlagFileHinter FlagFileHintFunc = withFileHint
+
+// FlagsByName is a slice of Flag.
+type FlagsByName []Flag
+
+func (f FlagsByName) Len() int {
+	return len(f)
+}
+
+func (f FlagsByName) Less(i, j int) bool {
+	return lexicographicLess(f[i].GetName(), f[j].GetName())
+}
+
+func (f FlagsByName) Swap(i, j int) {
+	f[i], f[j] = f[j], f[i]
+}
+
 // Flag is a common interface related to parsing flags in cli.
-// For more advanced flag parsing techniques, it is recomended that
+// For more advanced flag parsing techniques, it is recommended that
 // this interface be implemented.
 type Flag interface {
 	fmt.Stringer
 	// Apply Flag settings to the given flag set
 	Apply(*flag.FlagSet)
-	getName() string
 	IsRequired() bool
+	GetName() string
 }
 
-func flagSet(name string, flags []Flag) *flag.FlagSet {
+// errorableFlag is an interface that allows us to return errors during apply
+// it allows flags defined in this library to return errors in a fashion backwards compatible
+// TODO remove in v2 and modify the existing Flag interface to return errors
+type errorableFlag interface {
+	Flag
+
+	ApplyWithError(*flag.FlagSet) error
+}
+
+func flagSet(name string, flags []Flag) (*flag.FlagSet, error) {
 	set := flag.NewFlagSet(name, flag.ContinueOnError)
 
 	for _, f := range flags {
-		f.Apply(set)
+		//TODO remove in v2 when errorableFlag is removed
+		if ef, ok := f.(errorableFlag); ok {
+			if err := ef.ApplyWithError(set); err != nil {
+				return nil, err
+			}
+		} else {
+			f.Apply(set)
+		}
 	}
-	return set
+	return set, nil
 }
 
 func eachName(longName string, fn func(string)) {
@@ -80,42 +133,47 @@ func (f GenericFlag) String() string {
 
 // Apply takes the flagset and calls Set on the generic flag with the value
 // provided by the user for parsing by the flag
+// Ignores parsing errors
 func (f GenericFlag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
+}
+
+// ApplyWithError takes the flagset and calls Set on the generic flag with the value
+// provided by the user for parsing by the flag
+func (f GenericFlag) ApplyWithError(set *flag.FlagSet) error {
 	val := f.Value
-	if f.EnvVar != "" {
+	if fileEnvVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+		if err := val.Set(fileEnvVal); err != nil {
-			envVar = strings.TrimSpace(envVar)
+			return fmt.Errorf("could not parse %s as value for flag %s: %s", fileEnvVal, f.Name, err)
-			if envVal := os.Getenv(envVar); envVal != "" {
-				val.Set(envVal)
-				break
-			}
 		}
 	}
 
 	eachName(f.Name, func(name string) {
 		set.Var(f.Value, name, f.Usage)
 	})
-}
 
-func (f GenericFlag) getName() string {
+	return nil
-	return f.Name
 }
 
 func (f GenericFlag) IsRequired() bool {
 	return f.Required
 }
 
+// StringSlice is an opaque type for []string to satisfy flag.Value and flag.Getter
 type StringSlice []string
 
+// Set appends the string value to the list of values
 func (f *StringSlice) Set(value string) error {
 	*f = append(*f, value)
 	return nil
 }
 
+// String returns a readable representation of this value (for usage defaults)
 func (f *StringSlice) String() string {
 	return fmt.Sprintf("%s", *f)
 }
 
+// Value returns the slice of strings set by this flag
 func (f *StringSlice) Value() []string {
 	return *f
 }
@@ -134,52 +192,67 @@ func (f StringSliceFlag) String() string {
 	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s [%v]\t%v", prefixedNames(f.Name), pref+firstName+" option "+pref+firstName+" option", f.Usage))
 }
 
+// Get returns the slice of strings set by this flag
+func (f *StringSlice) Get() interface{} {
+	return *f
+}
+
+// Apply populates the flag given the flag set and environment
+// Ignores errors
 func (f StringSliceFlag) Apply(set *flag.FlagSet) {
-	if f.EnvVar != "" {
+	f.ApplyWithError(set)
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+}
-			envVar = strings.TrimSpace(envVar)
+
-			if envVal := os.Getenv(envVar); envVal != "" {
+// ApplyWithError populates the flag given the flag set and environment
-				newVal := &StringSlice{}
+func (f StringSliceFlag) ApplyWithError(set *flag.FlagSet) error {
-				for _, s := range strings.Split(envVal, ",") {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-					s = strings.TrimSpace(s)
+		newVal := &StringSlice{}
-					newVal.Set(s)
+		for _, s := range strings.Split(envVal, ",") {
-				}
+			s = strings.TrimSpace(s)
-				f.Value = newVal
+			if err := newVal.Set(s); err != nil {
-				break
+				return fmt.Errorf("could not parse %s as string value for flag %s: %s", envVal, f.Name, err)
 			}
 		}
+		if f.Value == nil {
+			f.Value = newVal
+		} else {
+			*f.Value = *newVal
+		}
 	}
 
 	eachName(f.Name, func(name string) {
+		if f.Value == nil {
+			f.Value = &StringSlice{}
+		}
 		set.Var(f.Value, name, f.Usage)
 	})
-}
 
-func (f StringSliceFlag) getName() string {
+	return nil
-	return f.Name
 }
 
 func (f StringSliceFlag) IsRequired() bool {
 	return f.Required
 }
 
+// IntSlice is an opaque type for []int to satisfy flag.Value and flag.Getter
 type IntSlice []int
 
+// Set parses the value into an integer and appends it to the list of values
 func (f *IntSlice) Set(value string) error {
-
 	tmp, err := strconv.Atoi(value)
 	if err != nil {
 		return err
-	} else {
-		*f = append(*f, tmp)
 	}
+	*f = append(*f, tmp)
 	return nil
 }
 
+// String returns a readable representation of this value (for usage defaults)
 func (f *IntSlice) String() string {
-	return fmt.Sprintf("%d", *f)
+	return fmt.Sprintf("%#v", *f)
 }
 
+// Value returns the slice of ints set by this flag
 func (f *IntSlice) Value() []int {
 	return *f
 }
@@ -198,32 +271,60 @@ func (f IntSliceFlag) String() string {
 	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s [%v]\t%v", prefixedNames(f.Name), pref+firstName+" option "+pref+firstName+" option", f.Usage))
 }
 
+// Get returns the slice of ints set by this flag
+func (f *IntSlice) Get() interface{} {
+	return *f
+}
+
+// Apply populates the flag given the flag set and environment
+// Ignores errors
 func (f IntSliceFlag) Apply(set *flag.FlagSet) {
-	if f.EnvVar != "" {
+	f.ApplyWithError(set)
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+}
-			envVar = strings.TrimSpace(envVar)
+
-			if envVal := os.Getenv(envVar); envVal != "" {
+// ApplyWithError populates the flag given the flag set and environment
-				newVal := &IntSlice{}
+func (f IntSliceFlag) ApplyWithError(set *flag.FlagSet) error {
-				for _, s := range strings.Split(envVal, ",") {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-					s = strings.TrimSpace(s)
+		newVal := &IntSlice{}
-					err := newVal.Set(s)
+		for _, s := range strings.Split(envVal, ",") {
-					if err != nil {
+			s = strings.TrimSpace(s)
-						fmt.Fprintf(os.Stderr, err.Error())
+			if err := newVal.Set(s); err != nil {
-					}
+				return fmt.Errorf("could not parse %s as int slice value for flag %s: %s", envVal, f.Name, err)
-				}
-				f.Value = newVal
-				break
 			}
 		}
+		if f.Value == nil {
+			f.Value = newVal
+		} else {
+			*f.Value = *newVal
+		}
 	}
 
 	eachName(f.Name, func(name string) {
+		if f.Value == nil {
+			f.Value = &IntSlice{}
+		}
 		set.Var(f.Value, name, f.Usage)
 	})
+
+	return nil
 }
 
-func (f IntSliceFlag) getName() string {
+// Int64Slice is an opaque type for []int to satisfy flag.Value and flag.Getter
-	return f.Name
+type Int64Slice []int64
+
+// Set parses the value into an integer and appends it to the list of values
+func (f *Int64Slice) Set(value string) error {
+	tmp, err := strconv.ParseInt(value, 10, 64)
+	if err != nil {
+		return err
+	}
+	*f = append(*f, tmp)
+	return nil
+}
+
+// String returns a readable representation of this value (for usage defaults)
+func (f *Int64Slice) String() string {
+	return fmt.Sprintf("%#v", *f)
 }
 
 func (f IntSliceFlag) IsRequired() bool {
@@ -241,28 +342,52 @@ func (f BoolFlag) String() string {
 	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s\t%v", prefixedNames(f.Name), f.Usage))
 }
 
-func (f BoolFlag) Apply(set *flag.FlagSet) {
+// Value returns the slice of ints set by this flag
-	val := false
+func (f *Int64Slice) Value() []int64 {
-	if f.EnvVar != "" {
+	return *f
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+}
-			envVar = strings.TrimSpace(envVar)
+
-			if envVal := os.Getenv(envVar); envVal != "" {
+// Get returns the slice of ints set by this flag
-				envValBool, err := strconv.ParseBool(envVal)
+func (f *Int64Slice) Get() interface{} {
-				if err == nil {
+	return *f
-					val = envValBool
+}
-				}
+
-				break
+// Apply populates the flag given the flag set and environment
+// Ignores errors
+func (f Int64SliceFlag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
+}
+
+// ApplyWithError populates the flag given the flag set and environment
+func (f Int64SliceFlag) ApplyWithError(set *flag.FlagSet) error {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
+		newVal := &Int64Slice{}
+		for _, s := range strings.Split(envVal, ",") {
+			s = strings.TrimSpace(s)
+			if err := newVal.Set(s); err != nil {
+				return fmt.Errorf("could not parse %s as int64 slice value for flag %s: %s", envVal, f.Name, err)
 			}
 		}
+		if f.Value == nil {
+			f.Value = newVal
+		} else {
+			*f.Value = *newVal
+		}
 	}
 
 	eachName(f.Name, func(name string) {
-		set.Bool(name, val, f.Usage)
+		if f.Value == nil {
+			f.Value = &Int64Slice{}
+		}
+		set.Var(f.Value, name, f.Usage)
 	})
+	return nil
 }
 
-func (f BoolFlag) getName() string {
+// Apply populates the flag given the flag set and environment
-	return f.Name
+// Ignores errors
+func (f BoolFlag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
 }
 
 func (f BoolFlag) IsRequired() bool {
@@ -280,28 +405,63 @@ func (f BoolTFlag) String() string {
 	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s\t%v", prefixedNames(f.Name), f.Usage))
 }
 
-func (f BoolTFlag) Apply(set *flag.FlagSet) {
+// ApplyWithError populates the flag given the flag set and environment
-	val := true
+func (f BoolFlag) ApplyWithError(set *flag.FlagSet) error {
-	if f.EnvVar != "" {
+	val := false
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-			envVar = strings.TrimSpace(envVar)
+		if envVal == "" {
-			if envVal := os.Getenv(envVar); envVal != "" {
+			val = false
-				envValBool, err := strconv.ParseBool(envVal)
+		} else {
-				if err == nil {
+			envValBool, err := strconv.ParseBool(envVal)
-					val = envValBool
+			if err != nil {
-					break
+				return fmt.Errorf("could not parse %s as bool value for flag %s: %s", envVal, f.Name, err)
-				}
 			}
+			val = envValBool
 		}
 	}
 
 	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.BoolVar(f.Destination, name, val, f.Usage)
+			return
+		}
 		set.Bool(name, val, f.Usage)
 	})
+
+	return nil
 }
 
-func (f BoolTFlag) getName() string {
+// Apply populates the flag given the flag set and environment
-	return f.Name
+// Ignores errors
+func (f BoolTFlag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
+}
+
+// ApplyWithError populates the flag given the flag set and environment
+func (f BoolTFlag) ApplyWithError(set *flag.FlagSet) error {
+	val := true
+
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
+		if envVal == "" {
+			val = false
+		} else {
+			envValBool, err := strconv.ParseBool(envVal)
+			if err != nil {
+				return fmt.Errorf("could not parse %s as bool value for flag %s: %s", envVal, f.Name, err)
+			}
+			val = envValBool
+		}
+	}
+
+	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.BoolVar(f.Destination, name, val, f.Usage)
+			return
+		}
+		set.Bool(name, val, f.Usage)
+	})
+
+	return nil
 }
 
 func (f BoolTFlag) IsRequired() bool {
@@ -316,37 +476,60 @@ type StringFlag struct {
 	Required bool
 }
 
-func (f StringFlag) String() string {
+// Apply populates the flag given the flag set and environment
-	var fmtString string
+// Ignores errors
-	fmtString = "%s %v\t%v"
+func (f StringFlag) Apply(set *flag.FlagSet) {
-
+	f.ApplyWithError(set)
-	if len(f.Value) > 0 {
-		fmtString = "%s \"%v\"\t%v"
-	} else {
-		fmtString = "%s %v\t%v"
-	}
-
-	return withHints(f.EnvVar, f.Required, fmt.Sprintf(fmtString, prefixedNames(f.Name), f.Value, f.Usage))
 }
 
-func (f StringFlag) Apply(set *flag.FlagSet) {
+// ApplyWithError populates the flag given the flag set and environment
-	if f.EnvVar != "" {
+func (f StringFlag) ApplyWithError(set *flag.FlagSet) error {
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-			envVar = strings.TrimSpace(envVar)
+		f.Value = envVal
-			if envVal := os.Getenv(envVar); envVal != "" {
-				f.Value = envVal
-				break
-			}
-		}
 	}
 
 	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.StringVar(f.Destination, name, f.Value, f.Usage)
+			return
+		}
 		set.String(name, f.Value, f.Usage)
 	})
+
+	return nil
 }
 
-func (f StringFlag) getName() string {
+// Apply populates the flag given the flag set and environment
-	return f.Name
+// Ignores errors
+func (f IntFlag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
+}
+
+// ApplyWithError populates the flag given the flag set and environment
+func (f IntFlag) ApplyWithError(set *flag.FlagSet) error {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
+		envValInt, err := strconv.ParseInt(envVal, 0, 64)
+		if err != nil {
+			return fmt.Errorf("could not parse %s as int value for flag %s: %s", envVal, f.Name, err)
+		}
+		f.Value = int(envValInt)
+	}
+
+	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.IntVar(f.Destination, name, f.Value, f.Usage)
+			return
+		}
+		set.Int(name, f.Value, f.Usage)
+	})
+
+	return nil
+}
+
+// Apply populates the flag given the flag set and environment
+// Ignores errors
+func (f Int64Flag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
 }
 
 func (f StringFlag) IsRequired() bool {
@@ -365,27 +548,54 @@ func (f IntFlag) String() string {
 	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage))
 }
 
-func (f IntFlag) Apply(set *flag.FlagSet) {
+// ApplyWithError populates the flag given the flag set and environment
-	if f.EnvVar != "" {
+func (f Int64Flag) ApplyWithError(set *flag.FlagSet) error {
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-			envVar = strings.TrimSpace(envVar)
+		envValInt, err := strconv.ParseInt(envVal, 0, 64)
-			if envVal := os.Getenv(envVar); envVal != "" {
+		if err != nil {
-				envValInt, err := strconv.ParseInt(envVal, 0, 64)
+			return fmt.Errorf("could not parse %s as int value for flag %s: %s", envVal, f.Name, err)
-				if err == nil {
-					f.Value = int(envValInt)
-					break
-				}
-			}
 		}
+
+		f.Value = envValInt
 	}
 
 	eachName(f.Name, func(name string) {
-		set.Int(name, f.Value, f.Usage)
+		if f.Destination != nil {
+			set.Int64Var(f.Destination, name, f.Value, f.Usage)
+			return
+		}
+		set.Int64(name, f.Value, f.Usage)
 	})
+
+	return nil
 }
 
-func (f IntFlag) getName() string {
+// Apply populates the flag given the flag set and environment
-	return f.Name
+// Ignores errors
+func (f UintFlag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
+}
+
+// ApplyWithError populates the flag given the flag set and environment
+func (f UintFlag) ApplyWithError(set *flag.FlagSet) error {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
+		envValInt, err := strconv.ParseUint(envVal, 0, 64)
+		if err != nil {
+			return fmt.Errorf("could not parse %s as uint value for flag %s: %s", envVal, f.Name, err)
+		}
+
+		f.Value = uint(envValInt)
+	}
+
+	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.UintVar(f.Destination, name, f.Value, f.Usage)
+			return
+		}
+		set.Uint(name, f.Value, f.Usage)
+	})
+
+	return nil
 }
 
 func (f IntFlag) IsRequired() bool {
@@ -404,27 +614,59 @@ func (f DurationFlag) String() string {
 	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage))
 }
 
-func (f DurationFlag) Apply(set *flag.FlagSet) {
+// Apply populates the flag given the flag set and environment
-	if f.EnvVar != "" {
+// Ignores errors
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+func (f Uint64Flag) Apply(set *flag.FlagSet) {
-			envVar = strings.TrimSpace(envVar)
+	f.ApplyWithError(set)
-			if envVal := os.Getenv(envVar); envVal != "" {
+}
-				envValDuration, err := time.ParseDuration(envVal)
+
-				if err == nil {
+// ApplyWithError populates the flag given the flag set and environment
-					f.Value = envValDuration
+func (f Uint64Flag) ApplyWithError(set *flag.FlagSet) error {
-					break
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-				}
+		envValInt, err := strconv.ParseUint(envVal, 0, 64)
-			}
+		if err != nil {
+			return fmt.Errorf("could not parse %s as uint64 value for flag %s: %s", envVal, f.Name, err)
 		}
+
+		f.Value = uint64(envValInt)
 	}
 
 	eachName(f.Name, func(name string) {
-		set.Duration(name, f.Value, f.Usage)
+		if f.Destination != nil {
+			set.Uint64Var(f.Destination, name, f.Value, f.Usage)
+			return
+		}
+		set.Uint64(name, f.Value, f.Usage)
 	})
+
+	return nil
 }
 
-func (f DurationFlag) getName() string {
+// Apply populates the flag given the flag set and environment
-	return f.Name
+// Ignores errors
+func (f DurationFlag) Apply(set *flag.FlagSet) {
+	f.ApplyWithError(set)
+}
+
+// ApplyWithError populates the flag given the flag set and environment
+func (f DurationFlag) ApplyWithError(set *flag.FlagSet) error {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
+		envValDuration, err := time.ParseDuration(envVal)
+		if err != nil {
+			return fmt.Errorf("could not parse %s as duration for flag %s: %s", envVal, f.Name, err)
+		}
+
+		f.Value = envValDuration
+	}
+
+	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.DurationVar(f.Destination, name, f.Value, f.Usage)
+			return
+		}
+		set.Duration(name, f.Value, f.Usage)
+	})
+	return nil
 }
 
 func (f DurationFlag) IsRequired() bool {
@@ -443,26 +685,43 @@ func (f Float64Flag) String() string {
 	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage))
 }
 
+// Apply populates the flag given the flag set and environment
+// Ignores errors
 func (f Float64Flag) Apply(set *flag.FlagSet) {
-	if f.EnvVar != "" {
+	f.ApplyWithError(set)
-		for _, envVar := range strings.Split(f.EnvVar, ",") {
+}
-			envVar = strings.TrimSpace(envVar)
+
-			if envVal := os.Getenv(envVar); envVal != "" {
+// ApplyWithError populates the flag given the flag set and environment
-				envValFloat, err := strconv.ParseFloat(envVal, 10)
+func (f Float64Flag) ApplyWithError(set *flag.FlagSet) error {
-				if err == nil {
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
-					f.Value = float64(envValFloat)
+		envValFloat, err := strconv.ParseFloat(envVal, 10)
-				}
+		if err != nil {
-			}
+			return fmt.Errorf("could not parse %s as float64 value for flag %s: %s", envVal, f.Name, err)
 		}
+
+		f.Value = float64(envValFloat)
 	}
 
 	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.Float64Var(f.Destination, name, f.Value, f.Usage)
+			return
+		}
 		set.Float64(name, f.Value, f.Usage)
 	})
+
+	return nil
 }
 
-func (f Float64Flag) getName() string {
+func visibleFlags(fl []Flag) []Flag {
-	return f.Name
+	visible := []Flag{}
+	for _, flag := range fl {
+		field := flagValue(flag).FieldByName("Hidden")
+		if !field.IsValid() || !field.Bool() {
+			visible = append(visible, flag)
+		}
+	}
+	return visible
 }
 
 func (f Float64Flag) IsRequired() bool {
@@ -479,22 +738,51 @@ func prefixFor(name string) (prefix string) {
 	return
 }
 
-func prefixedNames(fullName string) (prefixed string) {
+// Returns the placeholder, if any, and the unquoted usage string.
+func unquoteUsage(usage string) (string, string) {
+	for i := 0; i < len(usage); i++ {
+		if usage[i] == '`' {
+			for j := i + 1; j < len(usage); j++ {
+				if usage[j] == '`' {
+					name := usage[i+1 : j]
+					usage = usage[:i] + name + usage[j+1:]
+					return name, usage
+				}
+			}
+			break
+		}
+	}
+	return "", usage
+}
+
+func prefixedNames(fullName, placeholder string) string {
+	var prefixed string
 	parts := strings.Split(fullName, ",")
 	for i, name := range parts {
 		name = strings.Trim(name, " ")
 		prefixed += prefixFor(name) + name
+		if placeholder != "" {
+			prefixed += " " + placeholder
+		}
 		if i < len(parts)-1 {
 			prefixed += ", "
 		}
 	}
-	return
+	return prefixed
 }
 
 func withEnvHint(envVar, str string) string {
 	envText := ""
 	if envVar != "" {
-		envText = fmt.Sprintf(" [$%s]", strings.Join(strings.Split(envVar, ","), ", $"))
+		prefix := "$"
+		suffix := ""
+		sep := ", $"
+		if runtime.GOOS == "windows" {
+			prefix = "%"
+			suffix = "%"
+			sep = "%, %"
+		}
+		envText = " [" + prefix + strings.Join(strings.Split(envVar, ","), sep) + suffix + "]"
 	}
 	return str + envText
 }
@@ -510,3 +798,147 @@ func withRequiredHint(isRequired bool, str string) string {
 func withHints(envVar string, isRequired bool, str string) string {
 	return withRequiredHint(isRequired, withEnvHint(envVar, str))
 }
+
+func withFileHint(filePath, str string) string {
+	fileText := ""
+	if filePath != "" {
+		fileText = fmt.Sprintf(" [%s]", filePath)
+	}
+	return str + fileText
+}
+
+func flagValue(f Flag) reflect.Value {
+	fv := reflect.ValueOf(f)
+	for fv.Kind() == reflect.Ptr {
+		fv = reflect.Indirect(fv)
+	}
+	return fv
+}
+
+func stringifyFlag(f Flag) string {
+	fv := flagValue(f)
+
+	switch f.(type) {
+	case IntSliceFlag:
+		return FlagFileHinter(
+			fv.FieldByName("FilePath").String(),
+			FlagEnvHinter(
+				fv.FieldByName("EnvVar").String(),
+				stringifyIntSliceFlag(f.(IntSliceFlag)),
+			),
+		)
+	case Int64SliceFlag:
+		return FlagFileHinter(
+			fv.FieldByName("FilePath").String(),
+			FlagEnvHinter(
+				fv.FieldByName("EnvVar").String(),
+				stringifyInt64SliceFlag(f.(Int64SliceFlag)),
+			),
+		)
+	case StringSliceFlag:
+		return FlagFileHinter(
+			fv.FieldByName("FilePath").String(),
+			FlagEnvHinter(
+				fv.FieldByName("EnvVar").String(),
+				stringifyStringSliceFlag(f.(StringSliceFlag)),
+			),
+		)
+	}
+
+	placeholder, usage := unquoteUsage(fv.FieldByName("Usage").String())
+
+	needsPlaceholder := false
+	defaultValueString := ""
+
+	if val := fv.FieldByName("Value"); val.IsValid() {
+		needsPlaceholder = true
+		defaultValueString = fmt.Sprintf(" (default: %v)", val.Interface())
+
+		if val.Kind() == reflect.String && val.String() != "" {
+			defaultValueString = fmt.Sprintf(" (default: %q)", val.String())
+		}
+	}
+
+	if defaultValueString == " (default: )" {
+		defaultValueString = ""
+	}
+
+	if needsPlaceholder && placeholder == "" {
+		placeholder = defaultPlaceholder
+	}
+
+	usageWithDefault := strings.TrimSpace(usage + defaultValueString)
+
+	return FlagFileHinter(
+		fv.FieldByName("FilePath").String(),
+		FlagEnvHinter(
+			fv.FieldByName("EnvVar").String(),
+			FlagNamePrefixer(fv.FieldByName("Name").String(), placeholder)+"\t"+usageWithDefault,
+		),
+	)
+}
+
+func stringifyIntSliceFlag(f IntSliceFlag) string {
+	defaultVals := []string{}
+	if f.Value != nil && len(f.Value.Value()) > 0 {
+		for _, i := range f.Value.Value() {
+			defaultVals = append(defaultVals, strconv.Itoa(i))
+		}
+	}
+
+	return stringifySliceFlag(f.Usage, f.Name, defaultVals)
+}
+
+func stringifyInt64SliceFlag(f Int64SliceFlag) string {
+	defaultVals := []string{}
+	if f.Value != nil && len(f.Value.Value()) > 0 {
+		for _, i := range f.Value.Value() {
+			defaultVals = append(defaultVals, strconv.FormatInt(i, 10))
+		}
+	}
+
+	return stringifySliceFlag(f.Usage, f.Name, defaultVals)
+}
+
+func stringifyStringSliceFlag(f StringSliceFlag) string {
+	defaultVals := []string{}
+	if f.Value != nil && len(f.Value.Value()) > 0 {
+		for _, s := range f.Value.Value() {
+			if len(s) > 0 {
+				defaultVals = append(defaultVals, strconv.Quote(s))
+			}
+		}
+	}
+
+	return stringifySliceFlag(f.Usage, f.Name, defaultVals)
+}
+
+func stringifySliceFlag(usage, name string, defaultVals []string) string {
+	placeholder, usage := unquoteUsage(usage)
+	if placeholder == "" {
+		placeholder = defaultPlaceholder
+	}
+
+	defaultVal := ""
+	if len(defaultVals) > 0 {
+		defaultVal = fmt.Sprintf(" (default: %s)", strings.Join(defaultVals, ", "))
+	}
+
+	usageWithDefault := strings.TrimSpace(usage + defaultVal)
+	return FlagNamePrefixer(name, placeholder) + "\t" + usageWithDefault
+}
+
+func flagFromFileEnv(filePath, envName string) (val string, ok bool) {
+	for _, envVar := range strings.Split(envName, ",") {
+		envVar = strings.TrimSpace(envVar)
+		if envVal, ok := syscall.Getenv(envVar); ok {
+			return envVal, true
+		}
+	}
+	for _, fileVar := range strings.Split(filePath, ",") {
+		if data, err := ioutil.ReadFile(fileVar); err == nil {
+			return string(data), true
+		}
+	}
+	return "", false
+}

flag_generated.go

@@ -0,0 +1,640 @@
+package cli
+
+import (
+	"flag"
+	"strconv"
+	"time"
+)
+
+// WARNING: This file is generated!
+
+// BoolFlag is a flag with type bool
+type BoolFlag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Destination *bool
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f BoolFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f BoolFlag) GetName() string {
+	return f.Name
+}
+
+// Bool looks up the value of a local BoolFlag, returns
+// false if not found
+func (c *Context) Bool(name string) bool {
+	return lookupBool(name, c.flagSet)
+}
+
+// GlobalBool looks up the value of a global BoolFlag, returns
+// false if not found
+func (c *Context) GlobalBool(name string) bool {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupBool(name, fs)
+	}
+	return false
+}
+
+func lookupBool(name string, set *flag.FlagSet) bool {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseBool(f.Value.String())
+		if err != nil {
+			return false
+		}
+		return parsed
+	}
+	return false
+}
+
+// BoolTFlag is a flag with type bool that is true by default
+type BoolTFlag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Destination *bool
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f BoolTFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f BoolTFlag) GetName() string {
+	return f.Name
+}
+
+// BoolT looks up the value of a local BoolTFlag, returns
+// false if not found
+func (c *Context) BoolT(name string) bool {
+	return lookupBoolT(name, c.flagSet)
+}
+
+// GlobalBoolT looks up the value of a global BoolTFlag, returns
+// false if not found
+func (c *Context) GlobalBoolT(name string) bool {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupBoolT(name, fs)
+	}
+	return false
+}
+
+func lookupBoolT(name string, set *flag.FlagSet) bool {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseBool(f.Value.String())
+		if err != nil {
+			return false
+		}
+		return parsed
+	}
+	return false
+}
+
+// DurationFlag is a flag with type time.Duration (see https://golang.org/pkg/time/#ParseDuration)
+type DurationFlag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Value       time.Duration
+	Destination *time.Duration
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f DurationFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f DurationFlag) GetName() string {
+	return f.Name
+}
+
+// Duration looks up the value of a local DurationFlag, returns
+// 0 if not found
+func (c *Context) Duration(name string) time.Duration {
+	return lookupDuration(name, c.flagSet)
+}
+
+// GlobalDuration looks up the value of a global DurationFlag, returns
+// 0 if not found
+func (c *Context) GlobalDuration(name string) time.Duration {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupDuration(name, fs)
+	}
+	return 0
+}
+
+func lookupDuration(name string, set *flag.FlagSet) time.Duration {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := time.ParseDuration(f.Value.String())
+		if err != nil {
+			return 0
+		}
+		return parsed
+	}
+	return 0
+}
+
+// Float64Flag is a flag with type float64
+type Float64Flag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Value       float64
+	Destination *float64
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f Float64Flag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f Float64Flag) GetName() string {
+	return f.Name
+}
+
+// Float64 looks up the value of a local Float64Flag, returns
+// 0 if not found
+func (c *Context) Float64(name string) float64 {
+	return lookupFloat64(name, c.flagSet)
+}
+
+// GlobalFloat64 looks up the value of a global Float64Flag, returns
+// 0 if not found
+func (c *Context) GlobalFloat64(name string) float64 {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupFloat64(name, fs)
+	}
+	return 0
+}
+
+func lookupFloat64(name string, set *flag.FlagSet) float64 {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseFloat(f.Value.String(), 64)
+		if err != nil {
+			return 0
+		}
+		return parsed
+	}
+	return 0
+}
+
+// GenericFlag is a flag with type Generic
+type GenericFlag struct {
+	Name     string
+	Usage    string
+	EnvVar   string
+	FilePath string
+	Hidden   bool
+	Value    Generic
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f GenericFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f GenericFlag) GetName() string {
+	return f.Name
+}
+
+// Generic looks up the value of a local GenericFlag, returns
+// nil if not found
+func (c *Context) Generic(name string) interface{} {
+	return lookupGeneric(name, c.flagSet)
+}
+
+// GlobalGeneric looks up the value of a global GenericFlag, returns
+// nil if not found
+func (c *Context) GlobalGeneric(name string) interface{} {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupGeneric(name, fs)
+	}
+	return nil
+}
+
+func lookupGeneric(name string, set *flag.FlagSet) interface{} {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := f.Value, error(nil)
+		if err != nil {
+			return nil
+		}
+		return parsed
+	}
+	return nil
+}
+
+// Int64Flag is a flag with type int64
+type Int64Flag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Value       int64
+	Destination *int64
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f Int64Flag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f Int64Flag) GetName() string {
+	return f.Name
+}
+
+// Int64 looks up the value of a local Int64Flag, returns
+// 0 if not found
+func (c *Context) Int64(name string) int64 {
+	return lookupInt64(name, c.flagSet)
+}
+
+// GlobalInt64 looks up the value of a global Int64Flag, returns
+// 0 if not found
+func (c *Context) GlobalInt64(name string) int64 {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupInt64(name, fs)
+	}
+	return 0
+}
+
+func lookupInt64(name string, set *flag.FlagSet) int64 {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseInt(f.Value.String(), 0, 64)
+		if err != nil {
+			return 0
+		}
+		return parsed
+	}
+	return 0
+}
+
+// IntFlag is a flag with type int
+type IntFlag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Value       int
+	Destination *int
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f IntFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f IntFlag) GetName() string {
+	return f.Name
+}
+
+// Int looks up the value of a local IntFlag, returns
+// 0 if not found
+func (c *Context) Int(name string) int {
+	return lookupInt(name, c.flagSet)
+}
+
+// GlobalInt looks up the value of a global IntFlag, returns
+// 0 if not found
+func (c *Context) GlobalInt(name string) int {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupInt(name, fs)
+	}
+	return 0
+}
+
+func lookupInt(name string, set *flag.FlagSet) int {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseInt(f.Value.String(), 0, 64)
+		if err != nil {
+			return 0
+		}
+		return int(parsed)
+	}
+	return 0
+}
+
+// IntSliceFlag is a flag with type *IntSlice
+type IntSliceFlag struct {
+	Name     string
+	Usage    string
+	EnvVar   string
+	FilePath string
+	Hidden   bool
+	Value    *IntSlice
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f IntSliceFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f IntSliceFlag) GetName() string {
+	return f.Name
+}
+
+// IntSlice looks up the value of a local IntSliceFlag, returns
+// nil if not found
+func (c *Context) IntSlice(name string) []int {
+	return lookupIntSlice(name, c.flagSet)
+}
+
+// GlobalIntSlice looks up the value of a global IntSliceFlag, returns
+// nil if not found
+func (c *Context) GlobalIntSlice(name string) []int {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupIntSlice(name, fs)
+	}
+	return nil
+}
+
+func lookupIntSlice(name string, set *flag.FlagSet) []int {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := (f.Value.(*IntSlice)).Value(), error(nil)
+		if err != nil {
+			return nil
+		}
+		return parsed
+	}
+	return nil
+}
+
+// Int64SliceFlag is a flag with type *Int64Slice
+type Int64SliceFlag struct {
+	Name     string
+	Usage    string
+	EnvVar   string
+	FilePath string
+	Hidden   bool
+	Value    *Int64Slice
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f Int64SliceFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f Int64SliceFlag) GetName() string {
+	return f.Name
+}
+
+// Int64Slice looks up the value of a local Int64SliceFlag, returns
+// nil if not found
+func (c *Context) Int64Slice(name string) []int64 {
+	return lookupInt64Slice(name, c.flagSet)
+}
+
+// GlobalInt64Slice looks up the value of a global Int64SliceFlag, returns
+// nil if not found
+func (c *Context) GlobalInt64Slice(name string) []int64 {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupInt64Slice(name, fs)
+	}
+	return nil
+}
+
+func lookupInt64Slice(name string, set *flag.FlagSet) []int64 {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := (f.Value.(*Int64Slice)).Value(), error(nil)
+		if err != nil {
+			return nil
+		}
+		return parsed
+	}
+	return nil
+}
+
+// StringFlag is a flag with type string
+type StringFlag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Value       string
+	Destination *string
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f StringFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f StringFlag) GetName() string {
+	return f.Name
+}
+
+// String looks up the value of a local StringFlag, returns
+// "" if not found
+func (c *Context) String(name string) string {
+	return lookupString(name, c.flagSet)
+}
+
+// GlobalString looks up the value of a global StringFlag, returns
+// "" if not found
+func (c *Context) GlobalString(name string) string {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupString(name, fs)
+	}
+	return ""
+}
+
+func lookupString(name string, set *flag.FlagSet) string {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := f.Value.String(), error(nil)
+		if err != nil {
+			return ""
+		}
+		return parsed
+	}
+	return ""
+}
+
+// StringSliceFlag is a flag with type *StringSlice
+type StringSliceFlag struct {
+	Name     string
+	Usage    string
+	EnvVar   string
+	FilePath string
+	Hidden   bool
+	Value    *StringSlice
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f StringSliceFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f StringSliceFlag) GetName() string {
+	return f.Name
+}
+
+// StringSlice looks up the value of a local StringSliceFlag, returns
+// nil if not found
+func (c *Context) StringSlice(name string) []string {
+	return lookupStringSlice(name, c.flagSet)
+}
+
+// GlobalStringSlice looks up the value of a global StringSliceFlag, returns
+// nil if not found
+func (c *Context) GlobalStringSlice(name string) []string {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupStringSlice(name, fs)
+	}
+	return nil
+}
+
+func lookupStringSlice(name string, set *flag.FlagSet) []string {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := (f.Value.(*StringSlice)).Value(), error(nil)
+		if err != nil {
+			return nil
+		}
+		return parsed
+	}
+	return nil
+}
+
+// Uint64Flag is a flag with type uint64
+type Uint64Flag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Value       uint64
+	Destination *uint64
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f Uint64Flag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f Uint64Flag) GetName() string {
+	return f.Name
+}
+
+// Uint64 looks up the value of a local Uint64Flag, returns
+// 0 if not found
+func (c *Context) Uint64(name string) uint64 {
+	return lookupUint64(name, c.flagSet)
+}
+
+// GlobalUint64 looks up the value of a global Uint64Flag, returns
+// 0 if not found
+func (c *Context) GlobalUint64(name string) uint64 {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupUint64(name, fs)
+	}
+	return 0
+}
+
+func lookupUint64(name string, set *flag.FlagSet) uint64 {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseUint(f.Value.String(), 0, 64)
+		if err != nil {
+			return 0
+		}
+		return parsed
+	}
+	return 0
+}
+
+// UintFlag is a flag with type uint
+type UintFlag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Hidden      bool
+	Value       uint
+	Destination *uint
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f UintFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f UintFlag) GetName() string {
+	return f.Name
+}
+
+// Uint looks up the value of a local UintFlag, returns
+// 0 if not found
+func (c *Context) Uint(name string) uint {
+	return lookupUint(name, c.flagSet)
+}
+
+// GlobalUint looks up the value of a global UintFlag, returns
+// 0 if not found
+func (c *Context) GlobalUint(name string) uint {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupUint(name, fs)
+	}
+	return 0
+}
+
+func lookupUint(name string, set *flag.FlagSet) uint {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseUint(f.Value.String(), 0, 64)
+		if err != nil {
+			return 0
+		}
+		return uint(parsed)
+	}
+	return 0
+}

funcs.go

@@ -0,0 +1,44 @@
+package cli
+
+// BashCompleteFunc is an action to execute when the bash-completion flag is set
+type BashCompleteFunc func(*Context)
+
+// BeforeFunc is an action to execute before any subcommands are run, but after
+// the context is ready if a non-nil error is returned, no subcommands are run
+type BeforeFunc func(*Context) error
+
+// AfterFunc is an action to execute after any subcommands are run, but after the
+// subcommand has finished it is run even if Action() panics
+type AfterFunc func(*Context) error
+
+// ActionFunc is the action to execute when no subcommands are specified
+type ActionFunc func(*Context) error
+
+// CommandNotFoundFunc is executed if the proper command cannot be found
+type CommandNotFoundFunc func(*Context, string)
+
+// OnUsageErrorFunc is executed if an usage error occurs. This is useful for displaying
+// customized usage error messages.  This function is able to replace the
+// original error messages.  If this function is not set, the "Incorrect usage"
+// is displayed and the execution is interrupted.
+type OnUsageErrorFunc func(context *Context, err error, isSubcommand bool) error
+
+// ExitErrHandlerFunc is executed if provided in order to handle ExitError values
+// returned by Actions and Before/After functions.
+type ExitErrHandlerFunc func(context *Context, err error)
+
+// FlagStringFunc is used by the help generation to display a flag, which is
+// expected to be a single line.
+type FlagStringFunc func(Flag) string
+
+// FlagNamePrefixFunc is used by the default FlagStringFunc to create prefix
+// text for a flag's full name.
+type FlagNamePrefixFunc func(fullName, placeholder string) string
+
+// FlagEnvHintFunc is used by the default FlagStringFunc to annotate flag help
+// with the environment variable details.
+type FlagEnvHintFunc func(envVar, str string) string
+
+// FlagFileHintFunc is used by the default FlagStringFunc to annotate flag help
+// with the file path details.
+type FlagFileHintFunc func(filePath, str string) string

generate-flag-types

@@ -0,0 +1,256 @@
+#!/usr/bin/env python
+"""
+The flag types that ship with the cli library have many things in common, and
+so we can take advantage of the `go generate` command to create much of the
+source code from a list of definitions.  These definitions attempt to cover
+the parts that vary between flag types, and should evolve as needed.
+
+An example of the minimum definition needed is:
+
+    {
+      "name": "SomeType",
+      "type": "sometype",
+      "context_default": "nil"
+    }
+
+In this example, the code generated for the `cli` package will include a type
+named `SomeTypeFlag` that is expected to wrap a value of type `sometype`.
+Fetching values by name via `*cli.Context` will default to a value of `nil`.
+
+A more complete, albeit somewhat redundant, example showing all available
+definition keys is:
+
+    {
+      "name": "VeryMuchType",
+      "type": "*VeryMuchType",
+      "value": true,
+      "dest": false,
+      "doctail": " which really only wraps a []float64, oh well!",
+      "context_type": "[]float64",
+      "context_default": "nil",
+      "parser": "parseVeryMuchType(f.Value.String())",
+      "parser_cast": "[]float64(parsed)"
+    }
+
+The meaning of each field is as follows:
+
+               name (string) - The type "name", which will be suffixed with
+                               `Flag` when generating the type definition
+                               for `cli` and the wrapper type for `altsrc`
+               type (string) - The type that the generated `Flag` type for `cli`
+                               is expected to "contain" as its `.Value` member
+                value (bool) - Should the generated `cli` type have a `Value`
+                               member?
+                 dest (bool) - Should the generated `cli` type support a
+                               destination pointer?
+            doctail (string) - Additional docs for the `cli` flag type comment
+       context_type (string) - The literal type used in the `*cli.Context`
+                               reader func signature
+    context_default (string) - The literal value used as the default by the
+                               `*cli.Context` reader funcs when no value is
+                               present
+             parser (string) - Literal code used to parse the flag `f`,
+                               expected to have a return signature of
+                               (value, error)
+        parser_cast (string) - Literal code used to cast the `parsed` value
+                               returned from the `parser` code
+"""
+
+from __future__ import print_function, unicode_literals
+
+import argparse
+import json
+import os
+import subprocess
+import sys
+import tempfile
+import textwrap
+
+
+class _FancyFormatter(argparse.ArgumentDefaultsHelpFormatter,
+                      argparse.RawDescriptionHelpFormatter):
+    pass
+
+
+def main(sysargs=sys.argv[:]):
+    parser = argparse.ArgumentParser(
+        description='Generate flag type code!',
+        formatter_class=_FancyFormatter)
+    parser.add_argument(
+        'package',
+        type=str, default='cli', choices=_WRITEFUNCS.keys(),
+        help='Package for which flag types will be generated'
+    )
+    parser.add_argument(
+        '-i', '--in-json',
+        type=argparse.FileType('r'),
+        default=sys.stdin,
+        help='Input JSON file which defines each type to be generated'
+    )
+    parser.add_argument(
+        '-o', '--out-go',
+        type=argparse.FileType('w'),
+        default=sys.stdout,
+        help='Output file/stream to which generated source will be written'
+    )
+    parser.epilog = __doc__
+
+    args = parser.parse_args(sysargs[1:])
+    _generate_flag_types(_WRITEFUNCS[args.package], args.out_go, args.in_json)
+    return 0
+
+
+def _generate_flag_types(writefunc, output_go, input_json):
+    types = json.load(input_json)
+
+    tmp = tempfile.NamedTemporaryFile(suffix='.go', delete=False)
+    writefunc(tmp, types)
+    tmp.close()
+
+    new_content = subprocess.check_output(
+        ['goimports', tmp.name]
+    ).decode('utf-8')
+
+    print(new_content, file=output_go, end='')
+    output_go.flush()
+    os.remove(tmp.name)
+
+
+def _set_typedef_defaults(typedef):
+    typedef.setdefault('doctail', '')
+    typedef.setdefault('context_type', typedef['type'])
+    typedef.setdefault('dest', True)
+    typedef.setdefault('value', True)
+    typedef.setdefault('parser', 'f.Value, error(nil)')
+    typedef.setdefault('parser_cast', 'parsed')
+
+
+def _write_cli_flag_types(outfile, types):
+    _fwrite(outfile, """\
+        package cli
+
+        // WARNING: This file is generated!
+
+        """)
+
+    for typedef in types:
+        _set_typedef_defaults(typedef)
+
+        _fwrite(outfile, """\
+        // {name}Flag is a flag with type {type}{doctail}
+        type {name}Flag struct {{
+            Name string
+            Usage string
+            EnvVar string
+            FilePath string
+            Hidden bool
+        """.format(**typedef))
+
+        if typedef['value']:
+            _fwrite(outfile, """\
+            Value {type}
+            """.format(**typedef))
+
+        if typedef['dest']:
+            _fwrite(outfile, """\
+            Destination *{type}
+            """.format(**typedef))
+
+        _fwrite(outfile, "\n}\n\n")
+
+        _fwrite(outfile, """\
+            // String returns a readable representation of this value
+            // (for usage defaults)
+            func (f {name}Flag) String() string {{
+                return FlagStringer(f)
+            }}
+
+            // GetName returns the name of the flag
+            func (f {name}Flag) GetName() string {{
+                return f.Name
+            }}
+
+            // {name} looks up the value of a local {name}Flag, returns
+            // {context_default} if not found
+            func (c *Context) {name}(name string) {context_type} {{
+                return lookup{name}(name, c.flagSet)
+            }}
+
+            // Global{name} looks up the value of a global {name}Flag, returns
+            // {context_default} if not found
+            func (c *Context) Global{name}(name string) {context_type} {{
+                if fs := lookupGlobalFlagSet(name, c); fs != nil {{
+                    return lookup{name}(name, fs)
+                }}
+                return {context_default}
+            }}
+
+            func lookup{name}(name string, set *flag.FlagSet) {context_type} {{
+                f := set.Lookup(name)
+                if f != nil {{
+                    parsed, err := {parser}
+                    if err != nil {{
+                        return {context_default}
+                    }}
+                    return {parser_cast}
+                }}
+                return {context_default}
+            }}
+            """.format(**typedef))
+
+
+def _write_altsrc_flag_types(outfile, types):
+    _fwrite(outfile, """\
+        package altsrc
+
+        import (
+            "gopkg.in/urfave/cli.v1"
+        )
+
+        // WARNING: This file is generated!
+
+        """)
+
+    for typedef in types:
+        _set_typedef_defaults(typedef)
+
+        _fwrite(outfile, """\
+        // {name}Flag is the flag type that wraps cli.{name}Flag to allow
+        // for other values to be specified
+        type {name}Flag struct {{
+            cli.{name}Flag
+            set *flag.FlagSet
+        }}
+
+        // New{name}Flag creates a new {name}Flag
+        func New{name}Flag(fl cli.{name}Flag) *{name}Flag {{
+            return &{name}Flag{{{name}Flag: fl, set: nil}}
+        }}
+
+        // Apply saves the flagSet for later usage calls, then calls the
+        // wrapped {name}Flag.Apply
+        func (f *{name}Flag) Apply(set *flag.FlagSet) {{
+            f.set = set
+            f.{name}Flag.Apply(set)
+        }}
+
+        // ApplyWithError saves the flagSet for later usage calls, then calls the
+        // wrapped {name}Flag.ApplyWithError
+        func (f *{name}Flag) ApplyWithError(set *flag.FlagSet) error {{
+            f.set = set
+            return f.{name}Flag.ApplyWithError(set)
+        }}
+        """.format(**typedef))
+
+
+def _fwrite(outfile, text):
+    print(textwrap.dedent(text), end='', file=outfile)
+
+
+_WRITEFUNCS = {
+    'cli': _write_cli_flag_types,
+    'altsrc': _write_altsrc_flag_types
+}
+
+if __name__ == '__main__':
+    sys.exit(main())

help.go

@@ -1,137 +1,214 @@
 package cli
 
-import "fmt"
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"text/tabwriter"
+	"text/template"
+)
 
-// The text template for the Default help topic.
+// AppHelpTemplate is the text template for the Default help topic.
 // cli.go uses text/template to render templates. You can
 // render custom help text by setting this variable.
 var AppHelpTemplate = `NAME:
-   {{.Name}} - {{.Usage}}
+   {{.Name}}{{if .Usage}} - {{.Usage}}{{end}}
 
 USAGE:
-   {{.Name}} {{if .Flags}}[global options] {{end}}command{{if .Flags}} [command options]{{end}} [arguments...]
+   {{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}} {{if .VisibleFlags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}{{if .Version}}{{if not .HideVersion}}
 
 VERSION:
-   {{.Version}}{{if or .Author .Email}}
+   {{.Version}}{{end}}{{end}}{{if .Description}}
 
-AUTHOR:{{if .Author}}
+DESCRIPTION:
-  {{.Author}}{{if .Email}} - <{{.Email}}>{{end}}{{else}}
+   {{.Description}}{{end}}{{if len .Authors}}
-  {{.Email}}{{end}}{{end}}
+
+AUTHOR{{with $length := len .Authors}}{{if ne 1 $length}}S{{end}}{{end}}:
+   {{range $index, $author := .Authors}}{{if $index}}
+   {{end}}{{$author}}{{end}}{{end}}{{if .VisibleCommands}}
+
+COMMANDS:{{range .VisibleCategories}}{{if .Name}}
+
+   {{.Name}}:{{end}}{{range .VisibleCommands}}
+     {{join .Names ", "}}{{"\t"}}{{.Usage}}{{end}}{{end}}{{end}}{{if .VisibleFlags}}
 
-COMMANDS:
-   {{range .Commands}}{{.Name}}{{with .ShortName}}, {{.}}{{end}}{{ "\t" }}{{.Usage}}
-   {{end}}{{if .Flags}}
 GLOBAL OPTIONS:
-   {{range .Flags}}{{.}}
+   {{range $index, $option := .VisibleFlags}}{{if $index}}
-   {{end}}{{end}}
+   {{end}}{{$option}}{{end}}{{end}}{{if .Copyright}}
+
+COPYRIGHT:
+   {{.Copyright}}{{end}}
 `
 
-// The text template for the command help topic.
+// CommandHelpTemplate is the text template for the command help topic.
 // cli.go uses text/template to render templates. You can
 // render custom help text by setting this variable.
 var CommandHelpTemplate = `NAME:
-   {{.Name}} - {{.Usage}}
+   {{.HelpName}} - {{.Usage}}
 
 USAGE:
-   command {{.Name}}{{if .Flags}} [command options]{{end}} [arguments...]{{if .Description}}
+   {{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}}{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}{{if .Category}}
+
+CATEGORY:
+   {{.Category}}{{end}}{{if .Description}}
 
 DESCRIPTION:
-   {{.Description}}{{end}}{{if .Flags}}
+   {{.Description}}{{end}}{{if .VisibleFlags}}
 
 OPTIONS:
-   {{range .Flags}}{{.}}
+   {{range .VisibleFlags}}{{.}}
-   {{end}}{{ end }}
+   {{end}}{{end}}
 `
 
-// The text template for the subcommand help topic.
+// SubcommandHelpTemplate is the text template for the subcommand help topic.
 // cli.go uses text/template to render templates. You can
 // render custom help text by setting this variable.
 var SubcommandHelpTemplate = `NAME:
-   {{.Name}} - {{.Usage}}
+   {{.HelpName}} - {{if .Description}}{{.Description}}{{else}}{{.Usage}}{{end}}
 
 USAGE:
-   {{.Name}} command{{if .Flags}} [command options]{{end}} [arguments...]
+   {{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}} command{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}
 
-COMMANDS:
+COMMANDS:{{range .VisibleCategories}}{{if .Name}}
-   {{range .Commands}}{{.Name}}{{with .ShortName}}, {{.}}{{end}}{{ "\t" }}{{.Usage}}
+   {{.Name}}:{{end}}{{range .VisibleCommands}}
-   {{end}}{{if .Flags}}
+     {{join .Names ", "}}{{"\t"}}{{.Usage}}{{end}}
+{{end}}{{if .VisibleFlags}}
 OPTIONS:
-   {{range .Flags}}{{.}}
+   {{range .VisibleFlags}}{{.}}
    {{end}}{{end}}
 `
 
 var helpCommand = Command{
 	Name:      "help",
-	ShortName: "h",
+	Aliases:   []string{"h"},
 	Usage:     "Shows a list of commands or help for one command",
-	Action: func(c *Context) {
+	ArgsUsage: "[command]",
+	Action: func(c *Context) error {
 		args := c.Args()
 		if args.Present() {
-			ShowCommandHelp(c, args.First())
+			return ShowCommandHelp(c, args.First())
-		} else {
-			ShowAppHelp(c)
 		}
+
+		ShowAppHelp(c)
+		return nil
 	},
 }
 
 var helpSubcommand = Command{
 	Name:      "help",
-	ShortName: "h",
+	Aliases:   []string{"h"},
 	Usage:     "Shows a list of commands or help for one command",
-	Action: func(c *Context) {
+	ArgsUsage: "[command]",
+	Action: func(c *Context) error {
 		args := c.Args()
 		if args.Present() {
-			ShowCommandHelp(c, args.First())
+			return ShowCommandHelp(c, args.First())
-		} else {
-			ShowSubcommandHelp(c)
 		}
+
+		return ShowSubcommandHelp(c)
 	},
 }
 
-// Prints help for the App
+// Prints help for the App or Command
-type helpPrinter func(templ string, data interface{})
+type helpPrinter func(w io.Writer, templ string, data interface{})
 
-var HelpPrinter helpPrinter = nil
+// Prints help for the App or Command with custom template function.
+type helpPrinterCustom func(w io.Writer, templ string, data interface{}, customFunc map[string]interface{})
 
-// Prints version for the App
+// HelpPrinter is a function that writes the help output. If not set a default
+// is used. The function signature is:
+// func(w io.Writer, templ string, data interface{})
+var HelpPrinter helpPrinter = printHelp
+
+// HelpPrinterCustom is same as HelpPrinter but
+// takes a custom function for template function map.
+var HelpPrinterCustom helpPrinterCustom = printHelpCustom
+
+// VersionPrinter prints the version for the App
 var VersionPrinter = printVersion
 
-func ShowAppHelp(c *Context) {
+// ShowAppHelpAndExit - Prints the list of subcommands for the app and exits with exit code.
-	HelpPrinter(AppHelpTemplate, c.App)
+func ShowAppHelpAndExit(c *Context, exitCode int) {
+	ShowAppHelp(c)
+	os.Exit(exitCode)
 }
 
-// Prints the list of subcommands as the default app completion method
+// ShowAppHelp is an action that displays the help.
+func ShowAppHelp(c *Context) (err error) {
+	if c.App.CustomAppHelpTemplate == "" {
+		HelpPrinter(c.App.Writer, AppHelpTemplate, c.App)
+		return
+	}
+	customAppData := func() map[string]interface{} {
+		if c.App.ExtraInfo == nil {
+			return nil
+		}
+		return map[string]interface{}{
+			"ExtraInfo": c.App.ExtraInfo,
+		}
+	}
+	HelpPrinterCustom(c.App.Writer, c.App.CustomAppHelpTemplate, c.App, customAppData())
+	return nil
+}
+
+// DefaultAppComplete prints the list of subcommands as the default app completion method
 func DefaultAppComplete(c *Context) {
 	for _, command := range c.App.Commands {
-		fmt.Fprintln(c.App.Writer, command.Name)
+		if command.Hidden {
-		if command.ShortName != "" {
+			continue
-			fmt.Fprintln(c.App.Writer, command.ShortName)
+		}
+		if os.Getenv("_CLI_ZSH_AUTOCOMPLETE_HACK") == "1" {
+			for _, name := range command.Names() {
+				fmt.Fprintf(c.App.Writer, "%s:%s\n", name, command.Usage)
+			}
+		} else {
+			for _, name := range command.Names() {
+				fmt.Fprintf(c.App.Writer, "%s\n", name)
+			}
 		}
 	}
 }
 
-// Prints help for the given command
+// ShowCommandHelpAndExit - exits with code after showing help
-func ShowCommandHelp(c *Context, command string) {
+func ShowCommandHelpAndExit(c *Context, command string, code int) {
-	for _, c := range c.App.Commands {
+	ShowCommandHelp(c, command)
+	os.Exit(code)
+}
+
+// ShowCommandHelp prints help for the given command
+func ShowCommandHelp(ctx *Context, command string) error {
+	// show the subcommand help for a command with subcommands
+	if command == "" {
+		HelpPrinter(ctx.App.Writer, SubcommandHelpTemplate, ctx.App)
+		return nil
+	}
+
+	for _, c := range ctx.App.Commands {
 		if c.HasName(command) {
-			HelpPrinter(CommandHelpTemplate, c)
+			if c.CustomHelpTemplate != "" {
-			return
+				HelpPrinterCustom(ctx.App.Writer, c.CustomHelpTemplate, c, nil)
+			} else {
+				HelpPrinter(ctx.App.Writer, CommandHelpTemplate, c)
+			}
+			return nil
 		}
 	}
 
-	if c.App.CommandNotFound != nil {
+	if ctx.App.CommandNotFound == nil {
-		c.App.CommandNotFound(c, command)
+		return NewExitError(fmt.Sprintf("No help topic for '%v'", command), 3)
-	} else {
-		fmt.Fprintf(c.App.Writer, "No help topic for '%v'\n", command)
 	}
+
+	ctx.App.CommandNotFound(ctx, command)
+	return nil
 }
 
-// Prints help for the given subcommand
+// ShowSubcommandHelp prints help for the given subcommand
-func ShowSubcommandHelp(c *Context) {
+func ShowSubcommandHelp(c *Context) error {
-	ShowCommandHelp(c, c.Command.Name)
+	return ShowCommandHelp(c, c.Command.Name)
 }
 
-// Prints the version number of the App
+// ShowVersion prints the version number of the App
 func ShowVersion(c *Context) {
 	VersionPrinter(c)
 }
@@ -140,7 +217,7 @@ func printVersion(c *Context) {
 	fmt.Fprintf(c.App.Writer, "%v version %v\n", c.App.Name, c.App.Version)
 }
 
-// Prints the lists of commands within a given context
+// ShowCompletions prints the lists of commands within a given context
 func ShowCompletions(c *Context) {
 	a := c.App
 	if a != nil && a.BashComplete != nil {
@@ -148,7 +225,7 @@ func ShowCompletions(c *Context) {
 	}
 }
 
-// Prints the custom completions for a given command
+// ShowCommandCompletions prints the custom completions for a given command
 func ShowCommandCompletions(ctx *Context, command string) {
 	c := ctx.App.Command(command)
 	if c != nil && c.BashComplete != nil {
@@ -156,22 +233,56 @@ func ShowCommandCompletions(ctx *Context, command string) {
 	}
 }
 
-func checkVersion(c *Context) bool {
+func printHelpCustom(out io.Writer, templ string, data interface{}, customFunc map[string]interface{}) {
-	if c.GlobalBool("version") {
+	funcMap := template.FuncMap{
-		ShowVersion(c)
+		"join": strings.Join,
-		return true
+	}
+	if customFunc != nil {
+		for key, value := range customFunc {
+			funcMap[key] = value
+		}
 	}
 
-	return false
+	w := tabwriter.NewWriter(out, 1, 8, 2, ' ', 0)
+	t := template.Must(template.New("help").Funcs(funcMap).Parse(templ))
+	err := t.Execute(w, data)
+	if err != nil {
+		// If the writer is closed, t.Execute will fail, and there's nothing
+		// we can do to recover.
+		if os.Getenv("CLI_TEMPLATE_ERROR_DEBUG") != "" {
+			fmt.Fprintf(ErrWriter, "CLI TEMPLATE ERROR: %#v\n", err)
+		}
+		return
+	}
+	w.Flush()
+}
+
+func printHelp(out io.Writer, templ string, data interface{}) {
+	printHelpCustom(out, templ, data, nil)
+}
+
+func checkVersion(c *Context) bool {
+	found := false
+	if VersionFlag.GetName() != "" {
+		eachName(VersionFlag.GetName(), func(name string) {
+			if c.GlobalBool(name) || c.Bool(name) {
+				found = true
+			}
+		})
+	}
+	return found
 }
 
 func checkHelp(c *Context) bool {
-	if c.GlobalBool("h") || c.GlobalBool("help") {
+	found := false
-		ShowAppHelp(c)
+	if HelpFlag.GetName() != "" {
-		return true
+		eachName(HelpFlag.GetName(), func(name string) {
+			if c.GlobalBool(name) || c.Bool(name) {
+				found = true
+			}
+		})
 	}
-
+	return found
-	return false
 }
 
 func checkCommandHelp(c *Context, name string) bool {
@@ -184,7 +295,7 @@ func checkCommandHelp(c *Context, name string) bool {
 }
 
 func checkSubcommandHelp(c *Context) bool {
-	if c.GlobalBool("h") || c.GlobalBool("help") {
+	if c.Bool("h") || c.Bool("help") {
 		ShowSubcommandHelp(c)
 		return true
 	}
@@ -192,20 +303,43 @@ func checkSubcommandHelp(c *Context) bool {
 	return false
 }
 
-func checkCompletions(c *Context) bool {
+func checkShellCompleteFlag(a *App, arguments []string) (bool, []string) {
-	if (c.GlobalBool(BashCompletionFlag.Name) || c.Bool(BashCompletionFlag.Name)) && c.App.EnableBashCompletion {
+	if !a.EnableBashCompletion {
-		ShowCompletions(c)
+		return false, arguments
-		return true
 	}
 
-	return false
+	pos := len(arguments) - 1
+	lastArg := arguments[pos]
+
+	if lastArg != "--"+BashCompletionFlag.GetName() {
+		return false, arguments
+	}
+
+	return true, arguments[:pos]
+}
+
+func checkCompletions(c *Context) bool {
+	if !c.shellComplete {
+		return false
+	}
+
+	if args := c.Args(); args.Present() {
+		name := args.First()
+		if cmd := c.App.Command(name); cmd != nil {
+			// let the command handle the completion
+			return false
+		}
+	}
+
+	ShowCompletions(c)
+	return true
 }
 
 func checkCommandCompletions(c *Context, name string) bool {
-	if c.Bool(BashCompletionFlag.Name) && c.App.EnableBashCompletion {
+	if !c.shellComplete {
-		ShowCommandCompletions(c, name)
+		return false
-		return true
 	}
 
-	return false
+	ShowCommandCompletions(c, name)
+	return true
 }

help_test.go

@@ -0,0 +1,452 @@
+package cli
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func Test_ShowAppHelp_NoAuthor(t *testing.T) {
+	output := new(bytes.Buffer)
+	app := NewApp()
+	app.Writer = output
+
+	c := NewContext(app, nil, nil)
+
+	ShowAppHelp(c)
+
+	if bytes.Index(output.Bytes(), []byte("AUTHOR(S):")) != -1 {
+		t.Errorf("expected\n%snot to include %s", output.String(), "AUTHOR(S):")
+	}
+}
+
+func Test_ShowAppHelp_NoVersion(t *testing.T) {
+	output := new(bytes.Buffer)
+	app := NewApp()
+	app.Writer = output
+
+	app.Version = ""
+
+	c := NewContext(app, nil, nil)
+
+	ShowAppHelp(c)
+
+	if bytes.Index(output.Bytes(), []byte("VERSION:")) != -1 {
+		t.Errorf("expected\n%snot to include %s", output.String(), "VERSION:")
+	}
+}
+
+func Test_ShowAppHelp_HideVersion(t *testing.T) {
+	output := new(bytes.Buffer)
+	app := NewApp()
+	app.Writer = output
+
+	app.HideVersion = true
+
+	c := NewContext(app, nil, nil)
+
+	ShowAppHelp(c)
+
+	if bytes.Index(output.Bytes(), []byte("VERSION:")) != -1 {
+		t.Errorf("expected\n%snot to include %s", output.String(), "VERSION:")
+	}
+}
+
+func Test_Help_Custom_Flags(t *testing.T) {
+	oldFlag := HelpFlag
+	defer func() {
+		HelpFlag = oldFlag
+	}()
+
+	HelpFlag = BoolFlag{
+		Name:  "help, x",
+		Usage: "show help",
+	}
+
+	app := App{
+		Flags: []Flag{
+			BoolFlag{Name: "foo, h"},
+		},
+		Action: func(ctx *Context) error {
+			if ctx.Bool("h") != true {
+				t.Errorf("custom help flag not set")
+			}
+			return nil
+		},
+	}
+	output := new(bytes.Buffer)
+	app.Writer = output
+	app.Run([]string{"test", "-h"})
+	if output.Len() > 0 {
+		t.Errorf("unexpected output: %s", output.String())
+	}
+}
+
+func Test_Version_Custom_Flags(t *testing.T) {
+	oldFlag := VersionFlag
+	defer func() {
+		VersionFlag = oldFlag
+	}()
+
+	VersionFlag = BoolFlag{
+		Name:  "version, V",
+		Usage: "show version",
+	}
+
+	app := App{
+		Flags: []Flag{
+			BoolFlag{Name: "foo, v"},
+		},
+		Action: func(ctx *Context) error {
+			if ctx.Bool("v") != true {
+				t.Errorf("custom version flag not set")
+			}
+			return nil
+		},
+	}
+	output := new(bytes.Buffer)
+	app.Writer = output
+	app.Run([]string{"test", "-v"})
+	if output.Len() > 0 {
+		t.Errorf("unexpected output: %s", output.String())
+	}
+}
+
+func Test_helpCommand_Action_ErrorIfNoTopic(t *testing.T) {
+	app := NewApp()
+
+	set := flag.NewFlagSet("test", 0)
+	set.Parse([]string{"foo"})
+
+	c := NewContext(app, set, nil)
+
+	err := helpCommand.Action.(func(*Context) error)(c)
+
+	if err == nil {
+		t.Fatalf("expected error from helpCommand.Action(), but got nil")
+	}
+
+	exitErr, ok := err.(*ExitError)
+	if !ok {
+		t.Fatalf("expected ExitError from helpCommand.Action(), but instead got: %v", err.Error())
+	}
+
+	if !strings.HasPrefix(exitErr.Error(), "No help topic for") {
+		t.Fatalf("expected an unknown help topic error, but got: %v", exitErr.Error())
+	}
+
+	if exitErr.exitCode != 3 {
+		t.Fatalf("expected exit value = 3, got %d instead", exitErr.exitCode)
+	}
+}
+
+func Test_helpCommand_InHelpOutput(t *testing.T) {
+	app := NewApp()
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"test", "--help"})
+
+	s := output.String()
+
+	if strings.Contains(s, "\nCOMMANDS:\nGLOBAL OPTIONS:\n") {
+		t.Fatalf("empty COMMANDS section detected: %q", s)
+	}
+
+	if !strings.Contains(s, "help, h") {
+		t.Fatalf("missing \"help, h\": %q", s)
+	}
+}
+
+func Test_helpSubcommand_Action_ErrorIfNoTopic(t *testing.T) {
+	app := NewApp()
+
+	set := flag.NewFlagSet("test", 0)
+	set.Parse([]string{"foo"})
+
+	c := NewContext(app, set, nil)
+
+	err := helpSubcommand.Action.(func(*Context) error)(c)
+
+	if err == nil {
+		t.Fatalf("expected error from helpCommand.Action(), but got nil")
+	}
+
+	exitErr, ok := err.(*ExitError)
+	if !ok {
+		t.Fatalf("expected ExitError from helpCommand.Action(), but instead got: %v", err.Error())
+	}
+
+	if !strings.HasPrefix(exitErr.Error(), "No help topic for") {
+		t.Fatalf("expected an unknown help topic error, but got: %v", exitErr.Error())
+	}
+
+	if exitErr.exitCode != 3 {
+		t.Fatalf("expected exit value = 3, got %d instead", exitErr.exitCode)
+	}
+}
+
+func TestShowAppHelp_CommandAliases(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name:    "frobbly",
+				Aliases: []string{"fr", "frob"},
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"foo", "--help"})
+
+	if !strings.Contains(output.String(), "frobbly, fr, frob") {
+		t.Errorf("expected output to include all command aliases; got: %q", output.String())
+	}
+}
+
+func TestShowCommandHelp_CommandAliases(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name:    "frobbly",
+				Aliases: []string{"fr", "frob", "bork"},
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"foo", "help", "fr"})
+
+	if !strings.Contains(output.String(), "frobbly") {
+		t.Errorf("expected output to include command name; got: %q", output.String())
+	}
+
+	if strings.Contains(output.String(), "bork") {
+		t.Errorf("expected output to exclude command aliases; got: %q", output.String())
+	}
+}
+
+func TestShowSubcommandHelp_CommandAliases(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name:    "frobbly",
+				Aliases: []string{"fr", "frob", "bork"},
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"foo", "help"})
+
+	if !strings.Contains(output.String(), "frobbly, fr, frob, bork") {
+		t.Errorf("expected output to include all command aliases; got: %q", output.String())
+	}
+}
+
+func TestShowCommandHelp_Customtemplate(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name: "frobbly",
+				Action: func(ctx *Context) error {
+					return nil
+				},
+				HelpName: "foo frobbly",
+				CustomHelpTemplate: `NAME:
+   {{.HelpName}} - {{.Usage}}
+
+USAGE:
+   {{.HelpName}} [FLAGS] TARGET [TARGET ...]
+
+FLAGS:
+  {{range .VisibleFlags}}{{.}}
+  {{end}}
+EXAMPLES:
+   1. Frobbly runs with this param locally.
+      $ {{.HelpName}} wobbly
+`,
+			},
+		},
+	}
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"foo", "help", "frobbly"})
+
+	if strings.Contains(output.String(), "2. Frobbly runs without this param locally.") {
+		t.Errorf("expected output to exclude \"2. Frobbly runs without this param locally.\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "1. Frobbly runs with this param locally.") {
+		t.Errorf("expected output to include \"1. Frobbly runs with this param locally.\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "$ foo frobbly wobbly") {
+		t.Errorf("expected output to include \"$ foo frobbly wobbly\"; got: %q", output.String())
+	}
+}
+
+func TestShowSubcommandHelp_CommandUsageText(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name:      "frobbly",
+				UsageText: "this is usage text",
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+
+	app.Run([]string{"foo", "frobbly", "--help"})
+
+	if !strings.Contains(output.String(), "this is usage text") {
+		t.Errorf("expected output to include usage text; got: %q", output.String())
+	}
+}
+
+func TestShowSubcommandHelp_SubcommandUsageText(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name: "frobbly",
+				Subcommands: []Command{
+					{
+						Name:      "bobbly",
+						UsageText: "this is usage text",
+					},
+				},
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"foo", "frobbly", "bobbly", "--help"})
+
+	if !strings.Contains(output.String(), "this is usage text") {
+		t.Errorf("expected output to include usage text; got: %q", output.String())
+	}
+}
+
+func TestShowAppHelp_HiddenCommand(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name: "frobbly",
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+			{
+				Name:   "secretfrob",
+				Hidden: true,
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"app", "--help"})
+
+	if strings.Contains(output.String(), "secretfrob") {
+		t.Errorf("expected output to exclude \"secretfrob\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "frobbly") {
+		t.Errorf("expected output to include \"frobbly\"; got: %q", output.String())
+	}
+}
+
+func TestShowAppHelp_CustomAppTemplate(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name: "frobbly",
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+			{
+				Name:   "secretfrob",
+				Hidden: true,
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+		},
+		ExtraInfo: func() map[string]string {
+			platform := fmt.Sprintf("OS: %s | Arch: %s", runtime.GOOS, runtime.GOARCH)
+			goruntime := fmt.Sprintf("Version: %s | CPUs: %d", runtime.Version(), runtime.NumCPU())
+			return map[string]string{
+				"PLATFORM": platform,
+				"RUNTIME":  goruntime,
+			}
+		},
+		CustomAppHelpTemplate: `NAME:
+  {{.Name}} - {{.Usage}}
+
+USAGE:
+  {{.Name}} {{if .VisibleFlags}}[FLAGS] {{end}}COMMAND{{if .VisibleFlags}} [COMMAND FLAGS | -h]{{end}} [ARGUMENTS...]
+
+COMMANDS:
+  {{range .VisibleCommands}}{{join .Names ", "}}{{ "\t" }}{{.Usage}}
+  {{end}}{{if .VisibleFlags}}
+GLOBAL FLAGS:
+  {{range .VisibleFlags}}{{.}}
+  {{end}}{{end}}
+VERSION:
+  2.0.0
+{{"\n"}}{{range $key, $value := ExtraInfo}}
+{{$key}}:
+  {{$value}}
+{{end}}`,
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"app", "--help"})
+
+	if strings.Contains(output.String(), "secretfrob") {
+		t.Errorf("expected output to exclude \"secretfrob\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "frobbly") {
+		t.Errorf("expected output to include \"frobbly\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "PLATFORM:") ||
+		!strings.Contains(output.String(), "OS:") ||
+		!strings.Contains(output.String(), "Arch:") {
+		t.Errorf("expected output to include \"PLATFORM:, OS: and Arch:\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "RUNTIME:") ||
+		!strings.Contains(output.String(), "Version:") ||
+		!strings.Contains(output.String(), "CPUs:") {
+		t.Errorf("expected output to include \"RUNTIME:, Version: and CPUs:\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "VERSION:") ||
+		!strings.Contains(output.String(), "2.0.0") {
+		t.Errorf("expected output to include \"VERSION:, 2.0.0\"; got: %q", output.String())
+	}
+}

helpers_test.go

@@ -1,19 +1,28 @@
-package cli_test
+package cli
 
 import (
+	"os"
 	"reflect"
+	"runtime"
+	"strings"
 	"testing"
 )
 
-/* Test Helpers */
+var (
+	wd, _ = os.Getwd()
+)
+
 func expect(t *testing.T, a interface{}, b interface{}) {
-	if a != b {
+	_, fn, line, _ := runtime.Caller(1)
-		t.Errorf("Expected %v (type %v) - Got %v (type %v)", b, reflect.TypeOf(b), a, reflect.TypeOf(a))
+	fn = strings.Replace(fn, wd+"/", "", -1)
+
+	if !reflect.DeepEqual(a, b) {
+		t.Errorf("(%s:%d) Expected %v (type %v) - Got %v (type %v)", fn, line, b, reflect.TypeOf(b), a, reflect.TypeOf(a))
 	}
 }
 
 func refute(t *testing.T, a interface{}, b interface{}) {
-	if a == b {
+	if reflect.DeepEqual(a, b) {
 		t.Errorf("Did not expect %v (type %v) - Got %v (type %v)", b, reflect.TypeOf(b), a, reflect.TypeOf(a))
 	}
 }

helpers_unix_test.go

@@ -0,0 +1,9 @@
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package cli
+
+import "os"
+
+func clearenv() {
+	os.Clearenv()
+}

helpers_windows_test.go

@@ -0,0 +1,20 @@
+package cli
+
+import (
+	"os"
+	"syscall"
+)
+
+// os.Clearenv() doesn't actually unset variables on Windows
+// See: https://github.com/golang/go/issues/17902
+func clearenv() {
+	for _, s := range os.Environ() {
+		for j := 1; j < len(s); j++ {
+			if s[j] == '=' {
+				keyp, _ := syscall.UTF16PtrFromString(s[0:j])
+				syscall.SetEnvironmentVariable(keyp, nil)
+				break
+			}
+		}
+	}
+}

runtests

@@ -0,0 +1,122 @@
+#!/usr/bin/env python
+from __future__ import print_function
+
+import argparse
+import os
+import sys
+import tempfile
+
+from subprocess import check_call, check_output
+
+
+PACKAGE_NAME = os.environ.get(
+    'CLI_PACKAGE_NAME', 'github.com/urfave/cli'
+)
+
+
+def main(sysargs=sys.argv[:]):
+    targets = {
+        'vet': _vet,
+        'test': _test,
+        'gfmrun': _gfmrun,
+        'toc': _toc,
+        'gen': _gen,
+    }
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        'target', nargs='?', choices=tuple(targets.keys()), default='test'
+    )
+    args = parser.parse_args(sysargs[1:])
+
+    targets[args.target]()
+    return 0
+
+
+def _test():
+    if check_output('go version'.split()).split()[2] < 'go1.2':
+        _run('go test -v .')
+        return
+
+    coverprofiles = []
+    for subpackage in ['', 'altsrc']:
+        coverprofile = 'cli.coverprofile'
+        if subpackage != '':
+            coverprofile = '{}.coverprofile'.format(subpackage)
+
+        coverprofiles.append(coverprofile)
+
+        _run('go test -v'.split() + [
+            '-coverprofile={}'.format(coverprofile),
+            ('{}/{}'.format(PACKAGE_NAME, subpackage)).rstrip('/')
+        ])
+
+    combined_name = _combine_coverprofiles(coverprofiles)
+    _run('go tool cover -func={}'.format(combined_name))
+    os.remove(combined_name)
+
+
+def _gfmrun():
+    go_version = check_output('go version'.split()).split()[2]
+    if go_version < 'go1.3':
+        print('runtests: skip on {}'.format(go_version), file=sys.stderr)
+        return
+    _run(['gfmrun', '-c', str(_gfmrun_count()), '-s', 'README.md'])
+
+
+def _vet():
+    _run('go vet ./...')
+
+
+def _toc():
+    _run('node_modules/.bin/markdown-toc -i README.md')
+    _run('git diff --exit-code')
+
+
+def _gen():
+    go_version = check_output('go version'.split()).split()[2]
+    if go_version < 'go1.5':
+        print('runtests: skip on {}'.format(go_version), file=sys.stderr)
+        return
+
+    _run('go generate ./...')
+    _run('git diff --exit-code')
+
+
+def _run(command):
+    if hasattr(command, 'split'):
+        command = command.split()
+    print('runtests: {}'.format(' '.join(command)), file=sys.stderr)
+    check_call(command)
+
+
+def _gfmrun_count():
+    with open('README.md') as infile:
+        lines = infile.read().splitlines()
+        return len(filter(_is_go_runnable, lines))
+
+
+def _is_go_runnable(line):
+    return line.startswith('package main')
+
+
+def _combine_coverprofiles(coverprofiles):
+    combined = tempfile.NamedTemporaryFile(
+        suffix='.coverprofile', delete=False
+    )
+    combined.write('mode: set\n')
+
+    for coverprofile in coverprofiles:
+        with open(coverprofile, 'r') as infile:
+            for line in infile.readlines():
+                if not line.startswith('mode: '):
+                    combined.write(line)
+
+    combined.flush()
+    name = combined.name
+    combined.close()
+    return name
+
+
+if __name__ == '__main__':
+    sys.exit(main())

sort.go

@@ -0,0 +1,29 @@
+package cli
+
+import "unicode"
+
+// lexicographicLess compares strings alphabetically considering case.
+func lexicographicLess(i, j string) bool {
+	iRunes := []rune(i)
+	jRunes := []rune(j)
+
+	lenShared := len(iRunes)
+	if lenShared > len(jRunes) {
+		lenShared = len(jRunes)
+	}
+
+	for index := 0; index < lenShared; index++ {
+		ir := iRunes[index]
+		jr := jRunes[index]
+
+		if lir, ljr := unicode.ToLower(ir), unicode.ToLower(jr); lir != ljr {
+			return lir < ljr
+		}
+
+		if ir != jr {
+			return ir < jr
+		}
+	}
+
+	return i < j
+}

sort_test.go

@@ -0,0 +1,30 @@
+package cli
+
+import "testing"
+
+var lexicographicLessTests = []struct {
+	i        string
+	j        string
+	expected bool
+}{
+	{"", "a", true},
+	{"a", "", false},
+	{"a", "a", false},
+	{"a", "A", false},
+	{"A", "a", true},
+	{"aa", "a", false},
+	{"a", "aa", true},
+	{"a", "b", true},
+	{"a", "B", true},
+	{"A", "b", true},
+	{"A", "B", true},
+}
+
+func TestLexicographicLess(t *testing.T) {
+	for _, test := range lexicographicLessTests {
+		actual := lexicographicLess(test.i, test.j)
+		if test.expected != actual {
+			t.Errorf(`expected string "%s" to come before "%s"`, test.i, test.j)
+		}
+	}
+}