optionparser

Mature command line arguments processor for Go.

Inspired by Ruby's (OptionParser) command line arguments processor.

Installation

go get github.com/speedata/optionparser

Usage

op := optionparser.NewOptionParser()
op.On(arguments ...interface{})
...
err := op.Parse()

where arguments is one of:

• "-a": a short argument
• "--argument": a long argument
• "--argument [FOO]" a long argument with an optional parameter
• "--argument FOO" a long argument with a mandatory parameter
• "Some text": The description text for the command line parameter
• &aboolean: Set the given boolean to true if the argument is given, set to false if parameter is prefixed with no-, such as --no-foo.
• &astring: Set the string to the value of the given parameter
• function: Call the function. The function must have the signature func().
• map[string]string: Set an entry of the map to the value of the given parameter and the key of the argument.
• []string Set the slice values to a comma separated list.

Help usage

The options -h and --help are included by default. The example below output this on cmd -h:

Usage: [parameter] command
-h, --help                   Show this help
-a, --func                   call myfunc
    --bstring=FOO            set string to FOO
-c                           set boolean option (try -no-c)
-d, --dlong=VAL              set option
-e, --elong[=VAL]            set option with optional parameter
-f                           boolean option

Commands
      y                      Run command y
      z                      Run command z

Settings

After calling op := optionparser.NewOptionParser() you can set op.Banner to set the first line of the help output. The default value is Usage: [parameter] command.

To control the first and last column of the help output, set op.Start and op.Stop. The default values are the integer values of 30 and 79.

Example usage

package main

import (
	"fmt"
	"log"

	"github.com/speedata/optionparser"
)

func myfunc() {
	fmt.Println("myfunc called")
}

func main() {
	var somestring string
	var truefalse bool
	options := make(map[string]string)
	stringslice := []string{}

	op := optionparser.NewOptionParser()
	op.On("-a", "--func", "call myfunc", myfunc)
	op.On("--bstring FOO", "set string to FOO", &somestring)
	op.On("-c", "set boolean option (try -no-c)", options)
	op.On("-d", "--dlong VAL", "set option", options)
	op.On("-e", "--elong [VAL]", "set option with optional parameter", options)
	op.On("-f", "boolean option", &truefalse)
	op.On("-g VALUES", "give multiple values", &stringslice)

	op.Command("y", "Run command y")
	op.Command("z", "Run command z")

	err := op.Parse()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("string `somestring' is now %q\n", somestring)
	fmt.Printf("options %v\n", options)
	fmt.Printf("-f %v\n", truefalse)
	fmt.Printf("-g %v\n", stringslice)
	fmt.Printf("Extra: %#v\n", op.Extra)
}

and the output of go run main.go -a --bstring foo -c -d somevalue -e x -f -g a,b,c y z

is:

myfunc called
string `somestring' is now "foo"
options map[c:true dlong:somevalue elong:x]
-f true
-g [a b c]
Extra: []string{"y", "z"}

State: Actively maintained, and used in production. Without warranty, of course.
Maturity level: 5/5 (works well in all tested repositories, there will be no API change)
License: Free software (MIT License)
Installation: Just run go get github.com/speedata/optionparser
API documentation: https://pkg.go.dev/github.com/speedata/optionparser
Contact: gundlach@speedata.de, @speedata@typo.social
Repository: https://github.com/speedata/optionparser
Dependencies: None
Contribution: We like to get any kind of feedback (success stories, bug reports, merge requests, ...)