getopt-like behavior in Go

Question

How do I nicely parse a list of program parameters and automate handling \"--help\" and/or \"--version\" (such as \"program [-d value] [--abc] [FILE1]\") in Go?

Answer 1

From the section "Command Line UI", you have several libraries able to parse getopt-long parameters.

I tried, with a Go1.0.2:

• the code.google.com/p/opts-go (See its documentation), which isn't quite operational.
• the github.com/droundy/goopt (See its documentation), which has a complete set of examples.

Example:

package main

import (
    "fmt"
    goopt "github.com/droundy/goopt"
)

func main() {
    fmt.Println("flag")
    goopt.NoArg([]string{"--abc"}, "abc param, no value", noabc)

    goopt.Description = func() string {
        return "Example program for using the goopt flag library."
    }
    goopt.Version = "1.0"
    goopt.Summary = "goopt demonstration program"
    goopt.Parse(nil)
}

func noabc() error {
    fmt.Println("You should have an --abc parameter")
    return nil
}

Other default parameters provided with goopt:

 --help               Display the generated help message (calls Help())
 --create-manpage     Display a manpage generated by the goopt library (uses Author, Suite, etc)
 --list-options       List all known flags