Add time.Duration flag type

context.go

@@ -5,6 +5,7 @@ import (
 	"flag"
 	"strconv"
 	"strings"
+	"time"
 )
 
 // Context is a type that is passed through to
@@ -29,6 +30,11 @@ func (c *Context) Int(name string) int {
 	return lookupInt(name, c.flagSet)
 }
 
+// Looks up the value of a local time.Duration flag, returns 0 if no time.Duration flag exists
+func (c *Context) Duration(name string) time.Duration {
+	return lookupDuration(name, c.flagSet)
+}
+
 // Looks up the value of a local float64 flag, returns 0 if no float64 flag exists
 func (c *Context) Float64(name string) float64 {
 	return lookupFloat64(name, c.flagSet)
@@ -69,6 +75,11 @@ 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)
@@ -174,6 +185,18 @@ func lookupInt(name string, set *flag.FlagSet) int {
 	return 0
 }
 
+func lookupDuration(name string, set *flag.FlagSet) time.Duration {
+	f := set.Lookup(name)
+	if f != nil {
+		val, err := time.ParseDuration(f.Value.String())
+		if err == nil {
+			return val
+		}
+	}
+
+	return 0
+}
+
 func lookupFloat64(name string, set *flag.FlagSet) float64 {
 	f := set.Lookup(name)
 	if f != nil {

context_test.go

@@ -2,8 +2,10 @@ package cli_test
 
 import (
 	"flag"
-	"github.com/codegangsta/cli"
 	"testing"
+	"time"
+
+	"github.com/codegangsta/cli"
 )
 
 func TestNewContext(t *testing.T) {
@@ -26,6 +28,13 @@ func TestContext_Int(t *testing.T) {
 	expect(t, c.Int("myflag"), 12)
 }
 
+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)
+	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")

flag.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"time"
 )
 
 // This flag enables bash-completion for all commands and subcommands
@@ -318,6 +319,36 @@ func (f IntFlag) getName() string {
 	return f.Name
 }
 
+type DurationFlag struct {
+	Name   string
+	Value  time.Duration
+	Usage  string
+	EnvVar string
+}
+
+func (f DurationFlag) String() string {
+	return withEnvHint(f.EnvVar, fmt.Sprintf("%s '%v'\t%v", prefixedNames(f.Name), f.Value, f.Usage))
+}
+
+func (f DurationFlag) Apply(set *flag.FlagSet) {
+	if f.EnvVar != "" {
+		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+			envValDuration, err := time.ParseDuration(envVal)
+			if err == nil {
+				f.Value = envValDuration
+			}
+		}
+	}
+
+	eachName(f.Name, func(name string) {
+		set.Duration(name, f.Value, f.Usage)
+	})
+}
+
+func (f DurationFlag) getName() string {
+	return f.Name
+}
+
 type Float64Flag struct {
 	Name   string
 	Value  float64

flag_test.go

@@ -1,13 +1,13 @@
 package cli_test
 
 import (
-	"github.com/codegangsta/cli"
-
 	"fmt"
 	"os"
 	"reflect"
 	"strings"
 	"testing"
+
+	"github.com/codegangsta/cli"
 )
 
 var boolFlagTests = []struct {
@@ -151,6 +151,39 @@ func TestIntFlagWithEnvVarHelpOutput(t *testing.T) {
 	}
 }
 
+var durationFlagTests = []struct {
+	name     string
+	expected string
+}{
+	{"help", "--help '0'\t"},
+	{"h", "-h '0'\t"},
+}
+
+func TestDurationFlagHelpOutput(t *testing.T) {
+
+	for _, test := range durationFlagTests {
+		flag := cli.DurationFlag{Name: test.name}
+		output := flag.String()
+
+		if output != test.expected {
+			t.Errorf("%s does not match %s", output, test.expected)
+		}
+	}
+}
+
+func TestDurationFlagWithEnvVarHelpOutput(t *testing.T) {
+
+	os.Setenv("APP_BAR", "2h3m6s")
+	for _, test := range durationFlagTests {
+		flag := cli.DurationFlag{Name: test.name, EnvVar: "APP_BAR"}
+		output := flag.String()
+
+		if !strings.HasSuffix(output, " [$APP_BAR]") {
+			t.Errorf("%s does not end with [$APP_BAR]", output)
+		}
+	}
+}
+
 var intSliceFlagTests = []struct {
 	name     string
 	value    *cli.IntSlice