Imagine we're building a utility for joining MP3 files, something like mp3cat. We want the user to supply the file names as a list of command line arguments. We also want to support an --out/-o option so the user can specify an output filename and a --quiet/-q flag for turning down the program's verbosity.

First we need to create an ArgParser instance:

import argslib

parser = argslib.ArgParser()
parser.helptext = "Usage: mp3cat..."
parser.version = "1.0"

Supplying a helptext string for the parser activates an automatic --help/-h flag; similarly, supplying a version string activates an automatic --version/-v flag.

Now we can register our options and flags:

parser.option("out o")
parser.flag("quiet q")

That's it, we're done specifying our interface. Now we can parse the program's command line arguments:

parser.parse()

This will exit with a suitable error message if anything goes wrong. Now we can check if the --quiet flag was found:

if parser.found("quiet"):
    do_stuff()

And determine our output filepath:

filepath = parser.value("out") or "default.mp3"

Positional aguments are collected up in the parser's .args list:

for filename in parser.args:
    do_stuff()