Defining Independent FlagSets in GoLang

Question

The Go documentation (http://golang.org/pkg/flag/) says:

The FlagSet type allows one to define independent sets of flags, such as to implement subcomm

Answer 1

You are meant to distinguish between subcommands first, and then call Parse on the right FlagSet.

f1 := flag.NewFlagSet("f1", flag.ContinueOnError)
silent := f1.Bool("silent", false, "")
f2 := flag.NewFlagSet("f2", flag.ContinueOnError)
loud := f2.Bool("loud", false, "")

switch os.Args[1] {
  case "apply":
    if err := f1.Parse(os.Args[2:]); err == nil {
      fmt.Println("apply", *silent)
    }
  case "reset":
    if err := f2.Parse(os.Args[2:]); err == nil {
      fmt.Println("reset", *loud)
    }
}

http://play.golang.org/p/eaEEx_EReX

Answer 2

Just change these code

if err := f2.Parse(os.Args[1:]); err == nil {
    fmt.Println(*reset)
}

to

f2.Parse(os.Args[1:])
fmt.Println(*reset)

but the warning is just left on the console.if u wanna remove it ,modify /usr/local/go/src/flag/flag.go and recompile the golang .. or do a copy of flag package.

　　→_→ 怀疑的眼神~~