Minimize struct copying

by using pointer func receivers and slices of struct pointers where possible.

command.go

@@ -3,7 +3,6 @@ package cli
 import (
 	"fmt"
 	"io/ioutil"
-	"reflect"
 	"sort"
 	"strings"
 )
@@ -37,7 +36,7 @@ type Command struct {
 	// Execute this function if a usage error occurs.
 	OnUsageError OnUsageErrorFunc
 	// List of child commands
-	Subcommands Commands
+	Subcommands []*Command
 	// List of flags to parse
 	Flags []Flag
 	// Treat all flags as normal arguments if true
@@ -54,32 +53,26 @@ type Command struct {
 
 // 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 {
+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) {
+func (c *Command) Run(ctx *Context) (err error) {
 	if len(c.Subcommands) > 0 {
 		return c.startApp(ctx)
 	}
 
-	if !c.HideHelp && !reflect.DeepEqual(HelpFlag, BoolFlag{}) {
+	if !c.HideHelp && HelpFlag != nil {
 		// append help to flags
-		c.Flags = append(
-			c.Flags,
-			HelpFlag,
-		)
+		c.appendFlag(HelpFlag)
 	}
 
 	if ctx.App.EnableBashCompletion {
-		c.Flags = append(c.Flags, BashCompletionFlag)
+		c.appendFlag(BashCompletionFlag)
 	}
 
 	set := flagSet(c.Name, c.Flags)
@@ -156,13 +149,12 @@ func (c Command) Run(ctx *Context) (err error) {
 }
 
 // Names returns the names including short names and aliases.
-func (c Command) Names() []string {
-	names := []string{c.Name}
-	return append(names, c.Aliases...)
+func (c *Command) Names() []string {
+	return append([]string{c.Name}, c.Aliases...)
 }
 
 // HasName returns true if Command.Name matches given name
-func (c Command) HasName(name string) bool {
+func (c *Command) HasName(name string) bool {
 	for _, n := range c.Names() {
 		if n == name {
 			return true
@@ -171,7 +163,7 @@ func (c Command) HasName(name string) bool {
 	return false
 }
 
-func (c Command) startApp(ctx *Context) error {
+func (c *Command) startApp(ctx *Context) error {
 	app := NewApp()
 	app.Metadata = ctx.App.Metadata
 	// set the name and usage
@@ -201,7 +193,7 @@ func (c Command) startApp(ctx *Context) error {
 	app.Compiled = ctx.App.Compiled
 	app.Writer = ctx.App.Writer
 
-	app.categories = CommandCategories{}
+	app.categories = NewCommandCategories()
 	for _, command := range c.Subcommands {
 		app.categories = app.categories.AddCommand(command.Category, command)
 	}
@@ -231,6 +223,22 @@ func (c Command) startApp(ctx *Context) error {
 }
 
 // VisibleFlags returns a slice of the Flags with Hidden=false
-func (c Command) VisibleFlags() []Flag {
+func (c *Command) VisibleFlags() []Flag {
 	return visibleFlags(c.Flags)
 }
+
+func (c *Command) appendFlag(fl Flag) {
+	if !hasFlag(c.Flags, fl) {
+		c.Flags = append(c.Flags, fl)
+	}
+}
+
+func hasCommand(commands []*Command, command *Command) bool {
+	for _, existing := range commands {
+		if command == existing {
+			return true
+		}
+	}
+
+	return false
+}