Simple and powerful technique for defining command line arguments.

practical_argparse.py

import argparse 

def parsed_arguments(defaults: dict) -> argparse.Namespace:

    """
    Sets all variables defined in default_args() as command line arguments.
    (e.g. specify job_dir with: --job-dir [job_dir])

    Args:
        defaults: dict of default argument names and values. Any `_` will be replaced with `-`.

    Returns:
        argparse.Namespace

    """

    parser = argparse.ArgumentParser(
        formatter_class=argparse.ArgumentDefaultsHelpFormatter)

    for key, val in defaults.items():
        # Replace underscore in variable names with hyphen:
        key = key.replace('_', '-')

        t = type(val)
        kwargs = {}

        if t == list:
            kwargs['nargs'] = '*'  # inputs are space separated arguments

        if t == bool:
            t = int  # bool has to be given as 0/1

        parser.add_argument(
            '--' + key,
            default=val,
            type=t,
            help=t.__name__,
            **kwargs
        )

    return parser.parse_args()



def default_args():
    batch_size = 32
    job_dir = ''

    return locals()


def process_flags(flags):
    if flags.job_dir == '':
        flags.job_dir = None


def parse():

    """
    Sets all variables defined in default_args() as command line arguments.

    (e.g. specify job_dir with: --job-dir [job_dir])
    """

    all_defaults = default_args()
    parsed_arguments(all_defaults)

    return parsed_arguments


def main():
    flags = parse()
    process_flags(flags)
    print(flags.job_dir)
    
    # If you need all arguments, e.g. for writing to disk as text:
    for k, v in flags.__dict__.items():
        print('{}: {}'.format(k, v))