getopt-like behavior in Go

Google has created a getopt package (import "github.com/pborman/getopt") which provides the more standard command line parsing (vs the 'flag' package).

package main

import (
    "fmt"
    "os"
    "github.com/pborman/getopt"
)

func main() {
    optName := getopt.StringLong("name", 'n', "", "Your name")
    optHelp := getopt.BoolLong("help", 0, "Help")
    getopt.Parse()

    if *optHelp {
        getopt.Usage()
        os.Exit(0)
    }

    fmt.Println("Hello " + *optName + "!")
}

 

$ ./hello --help
Usage: hello [--help] [-n value] [parameters ...]
     --help        Help
 -n, --name=value  Your name

$ ./hello --name Bob
Hello Bob!

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

Use the 'flag' package: http://golang.org/pkg/flag/. It doesn't do double-dash arguments, however. There isn't anything that exactly mimics GNU getopt behaviour (yet.)