python argparse sub command decorator

subcommand.py

import argparse

# Expose argparser into global scope
_parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
_subcmds = _parser.add_subparsers(
    title="Commands",
    description="Available actions",
    dest="subcmd")

# Subcommand argparse decorator
def subcommand(args=[], subcmds=_subcmds):
    """Decorator to convert a function into a new argparse subcommand, by
    calling subcmds.add_parser() with name and docstring from the decoratee as
    name and description, and optionally call subparser.add_argument() if args
    is provided. Example and recommanded usage:

    ```
    @subcommand()
    def subscribe(*args):
       "this is subscription"
       pass

    if __name__ == '__main__':
        args = _parser.parse_args()
        if args.subcmd:
            args.subcmdfunc(args)
        else:
            _parser.print_help()
    ```

    Args:
      args (list): list of lists, each will be arguments to parser.add_argument()
      subcmds (argparse object): subparser object created by add_subparser(),
                                 use _subcmds by default
    """
    def _decorator(function):
        parser = subcmds.add_parser(function.__name__, description=function.__doc__)
        for arg in args:
            parser.add_argument(*arg)
        parser.set_defaults(subcmdfunc=function)
        return function
    return _decorator

@subcommand()
def alpha(*args):
    """job alpha
    """
    print("alpha done")

@subcommand()
def beta(*args):
    """job beta
    """
    print("beta done")

def main():
    "demonstration of subcommand in argparse"
    args = _parser.parse_args()
    if args.subcmd:
        print("Calling %s()" % args.subcmd)
        args.subcmdfunc(args)
    else:
        _parser.print_help()
    print("Calling beta() directly")
    beta()

_parser.description = main.__doc__
if __name__ == '__main__':
    main()