argparse_with_subcommands.py

import argparse
import sys
import os


def main():
    '''
    Entry point of script
    '''
    # Parse arguments into script
    args = parse_raw_args(sys.argv[1:])

    # If we don't want verbose output, ignore all print statements
    if not args.verbose:
        # Redirect print output to null device on operating system
        print_redirect = open(os.devnull, 'w')
        sys.stdout = print_redirect


def parse_raw_args(args):
    '''
    Returns parsed and validated arguments that were passed into the script.
    :param args: The arguments passed into the script
    '''
    # Setup main parser
    parser = argparse.ArgumentParser()
    parser.add_argument('--verbose', dest='verbose', default=True,
                        action='store_true', help='Verbose output')

    # Initialize sub_command called to be None
    parser.set_defaults(sub_command=None)
    subparsers = parser.add_subparsers(help='Sub-Command Help (add --help after command for more help)')

    # Add subparsers
    subparsers = _add_something_subparser(subparsers)

    # TODO add more subparsers

    return parser.parse_args()


def _add_something_subparser(subparsers):
    something_parser = subparsers.add_parser('add_something', help='Adds a something with information')
    something_parser.add_argument('required',
                                  help='required argument')
    something_parser.add_argument('--opt', dest='optional', default=None,
                                  help='optional argument')
    # Set the sub_command called to be add_something. This happens only if this
    # parser gets used during parse_args() call below
    something_parser.set_defaults(sub_command='add_something')

    return subparsers

if __name__ == '__main__':
    main()