Generic parsers as flag types

context.go

@@ -58,6 +58,11 @@ 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)
@@ -83,6 +88,11 @@ 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 exists
 func (c *Context) IsSet(name string) bool {
 	if c.setFlags == nil {
@@ -184,6 +194,14 @@ func lookupIntSlice(name string, set *flag.FlagSet) []int {
 	return nil
 }
 
+func lookupGeneric(name string, set *flag.FlagSet) interface{} {
+	f := set.Lookup(name)
+	if f != nil {
+		return (f.Value.(Generic)).Value()
+	}
+	return nil
+}
+
 func lookupBool(name string, set *flag.FlagSet) bool {
 	f := set.Lookup(name)
 	if f != nil {
@@ -197,7 +215,6 @@ func lookupBool(name string, set *flag.FlagSet) bool {
 	return false
 }
 
-
 func lookupBoolT(name string, set *flag.FlagSet) bool {
 	f := set.Lookup(name)
 	if f != nil {

flag.go

@@ -37,6 +37,34 @@ func eachName(longName string, fn func(string)) {
 	}
 }
 
+// Generic is a generic parseable type identified by a specific flag
+type Generic interface {
+	Set(value string) error
+	String() string
+	Value() interface{}
+}
+
+// GenericFlag is the flag type for types implementing Generic
+type GenericFlag struct {
+	Name  string
+	Value Generic
+	Usage string
+}
+
+func (f GenericFlag) String() string {
+	return fmt.Sprintf("%s%s %v\t`%v` %s", prefixFor(f.Name), f.Name, f.Value, "-"+f.Name+" option -"+f.Name+" option", f.Usage)
+}
+
+func (f GenericFlag) Apply(set *flag.FlagSet) {
+	eachName(f.Name, func(name string) {
+		set.Var(f.Value, name, f.Usage)
+	})
+}
+
+func (f GenericFlag) getName() string {
+	return f.Name
+}
+
 type StringSlice []string
 
 func (f *StringSlice) Set(value string) error {

flag_test.go

@@ -2,7 +2,10 @@ package cli_test
 
 import (
 	"github.com/codegangsta/cli"
+
+	"fmt"
 	"reflect"
+	"strings"
 	"testing"
 )
 
@@ -154,3 +157,42 @@ func TestParseMultiBool(t *testing.T) {
 	}
 	a.Run([]string{"run", "--serve"})
 }
+
+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])
+}
+
+func (p *Parser) Value() interface{} {
+	return p
+}
+
+func TestParseGeneric(t *testing.T) {
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.GenericFlag{Name: "serve, s", Value: &Parser{}},
+		},
+		Action: func(ctx *cli.Context) {
+			if !reflect.DeepEqual(ctx.Generic("serve"), &Parser{"10", "20"}) {
+				t.Errorf("main name not set")
+			}
+			if !reflect.DeepEqual(ctx.Generic("s"), &Parser{"10", "20"}) {
+				t.Errorf("short name not set")
+			}
+		},
+	}
+	a.Run([]string{"run", "-s", "10,20"})
+}