skapt

Lightweight package for building command line apps in Go

I was inspired from other command line libraries to do my own package in Go.

API example

Example of command line with two arguments. One flag is required to be explicitly passed.

All the code in this example is written in one main.go file.

package main

import (
	"fmt"
	"os"
	"time"

	"github.com/hoenirvili/skapt"
	"github.com/hoenirvili/skapt/argument"
	"github.com/hoenirvili/skapt/flag"
)

func main() {
	app := skapt.Application{
		Name:        "Example",
		Description: "Example is an example of command line app",
		Version:     "1.0.0",
		Handler: func(ctx *skapt.Context) error {
			w := ctx.Int("wait")
			wait := time.Duration(w)
			exp := ctx.String("e")
			time.Sleep(wait * time.Second)
			_, err := fmt.Fprintf(ctx.Stdout, exp)
			return err
		},
		Flags: flag.Flags{{
			Short: "e", Long: "exp",
			Description: "Print something funny",
			Type:        argument.String,
			Required:	 true,
		}, {
			Short: "w", Long: "wait",
			Description: "How many seconds to wait until you print",
			Type:        argument.Int,
		}},
	}
	app.Exec(os.Args)
}

If we try to pass a long argument --help than we get this auto-generated output.

By default we append help and version flags if the Flags slice does not contain any of them.

Help output

$ : main --help
Usage: Example [OPTIONS] [ARG...]
       Example [ --help | -h | -v | --version ]

Example is an example of command line app

Options:

-e --exp      Print something funny
-w --wait     How many seconds to wait until you print
-h --help     Print out the help menu
-v --version  Print out the version of the program

For the version flag.

Version output

$ : main -v
Version 1.0.0
$ : main --version
Version 1.0.0

In our Application struct we declared 2 flags, -e/--exp and -w/--wait, if we pass valid values, the program sleeps 3 seconds and outputs the message passed in -e.

Run output

$ : main -e "Example text" --wait=3
Example text

Error output

We treat all basic errors by default.

$ : main
Option -e --exp is required

This also checks if the value passed is valid.

$ : main -w fjsuiajfsd
Cannot parse value "fjsiadufj" as int

FAQ

1. Why should I use this package instead of a more popular one?

   Really, nothing is stopping you to use one that is more battle tested, a more matured package.
   The reason for developing another command line parsing package was that I often want to write
   a simple lightweight command line app and I don't need more features than some basic flag value checking
   and a simpler flag value retrieval api.

2. Why not standard lib one?

   I didn't like the interface they provided and their flag value retrieval.