A quick argparse for scripts that share options

args.py

import argparse


DEFAULT_SERVER_HOST = "127.0.0.1"
DEFAULT_SERVER_PORT = 5555
DEFAULT_TIMEOUT = 500

BASE_ARGS = (
    (
        "Inputs",  # GROUP
        "-H",  # FLAG
        "--host",  # FLAG
        dict(  # OPTIONS
            metavar="HOST",
            help="Server host address (default: {})".format(
                DEFAULT_SERVER_HOST
            ),
            default=DEFAULT_SERVER_HOST,
        ),
    ),
    (
        "Inputs",
        "-P",
        "--port",
        dict(
            metavar="PORT",
            help="Server port (default: {})".format(DEFAULT_SERVER_PORT),
            default=DEFAULT_SERVER_PORT,
        ),
    ),
    (
        "Outputs",
        "-o",
        dict(metavar="OUTPUT", type=str, help="Output filename", required=True),
    ),
    (
        "",  # No group
        "--timeout",
        dict(
            metavar="TIMEOUT",
            type=int,
            help="Connection timeout in seconds (default: {})".format(
                DEFAULT_TIMEOUT
            ),
            default=DEFAULT_TIMEOUT,
        ),
    ),
)


def get_args(default_args=None, extra_args=None, prog=""):
    if default_args is None:
        args = BASE_ARGS
    else:
        args = default_args

    if extra_args is not None:
        args = args + extra_args

    parser = argparse.ArgumentParser(prog)
    groups = {g: parser.add_argument_group(g) for g, *_ in args if g}

    for group, *flags, opts in args:
        if group in groups:
            groups.get(group).add_argument(*flags, **opts)
        else:
            parser.add_argument(*flags, **opts)

    return parser, parser.parse_args()

def main():
    extra_args = (
        (
            "", 
            "--log-file",
            dict(
                metavar="LOG-FILE",
                help="File to write logs to",
            ),
        ),
    )

    parser, args = get_args(extra_args=extra_args, prog="My script")
    print(args)
    
if __name__ == "__main__":
    main()