Can command line flags in Go be set to mandatory?

Question

Is there a way how to set that certain flags are mandatory, or do I have to check for their presence on my own?

Answer 1

Or you could docopt, where you only have to write the "usage" text. Docopt interprets the usage text and creates an argument map. This opens up a whole lot of possibilities, all following the POSIX usage text standard. This library is available for about 20 languages already.

https://github.com/docopt/docopt.go

package main

import (
        "fmt"
        "github.com/docopt/docopt-go"
)

const (
        Usage = `Naval Fate.

Usage:
  naval_fate ship new <name>...
  naval_fate ship <name> move <x> <y> [--speed=<kn>]
  naval_fate ship shoot <x> <y>
  naval_fate mine (set|remove) <x> <y> [--moored|--drifting]
  naval_fate -h | --help
  naval_fate --version

Options:
  -h --help     Show this screen.
  --version     Show version.
  --speed=<kn>  Speed in knots [default: 10].
  --moored      Moored (anchored) mine.
  --drifting    Drifting mine.`
)

func main() {
        args, _ := docopt.ParseDoc(Usage)
        fmt.Println(args)
}