Simple command line parsing using Python's argparse module.

cmdline.py

"Simple command line parsing using argparse."
from collections import namedtuple
from functools import partial
import argparse

__all__ = ['Argument', 'parse_cmdline']

class Argument(namedtuple('BaseArgument', 'short full default help')):
    """Command line argument option for command line parser.
    
    If both short and full are None the argument is a positional argument.
    Otherwise short is a single character opton and full is a long name
    option.
    """

    def __new__(self, short=None, full=None, default=None, help=None):
        return super(Argument, self).__new__(Argument,
                short, full, default, help)

def parse_cmdline(arguments, description=None, epilog=None,
        known_args=False, cmdline=None):
    """Parse a command line using the arguments dictionary.

    The arguments dictionary keys are the option names. Values are either
    an Argument instance or a string. If the value is a string it's used for
    the option flag, short or long depending on length.
    """
    parser = argparse.ArgumentParser(description=description, epilog=epilog)
    for name in sorted(arguments):
        if isinstance(arguments[name], Argument):
            _add_advanced_argument(parser, name, arguments[name])
        else:
            _add_simple_argument(parser, name, arguments[name])
    if known_args:
        return parser.parse_known_args(cmdline)
    return parser.parse_args(cmdline)

def _add_simple_argument(parser, name, default):
    flag = '--' + name if len(name) > 1 else '-' + name
    action = 'store'
    if isinstance(default, bool):
        action = 'store_true' if not default else 'store_false'
    parser.add_argument(flag, action=action, default=default)

def _add_advanced_argument(parser, name, args):
    flags = []
    if args.short:
        flags.append('-' + args.short[:1])
    if args.full:
        flags.append('--' + args.full)
    default = args.default
    action = 'store'
    if isinstance(default, bool):
        action = 'store_true' if not default else 'store_false'
    parser.add_argument(*flags, dest=name, action=action, default=default,
            help=args.help)

demo_cmdline.py

"Demonstrate cmdline module usage."
from cmdline import Argument, parse_cmdline

if __name__ == '__main__':

    arguments = {
            'natural': 1,
            'w': True,
            'real': Argument('r', 'rea', 3.14, 'a real number'),
            'hello': Argument(None, 'hello', 'world', 'a string'),
            'japanese': Argument('j', 'japanese',
                u'\u30cf\u30ed\u30fc\u30ef\u30fc\u30eb\u30c9', None),
            'verbose': Argument('v',None, False, 'verbosity flag'),
            'target': Argument(None, None, None, 'a file name'),
    }

    print parse_cmdline(arguments, known_args=True,
            description=__doc__)

output.txt

usage: cmdline_demo.py [-h] [--hello HELLO] [-j JAPANESE] [--natural NATURAL]
                       [-r REAL] [-v] [-w]
                       target

Demonstrate cmdline module usage.

positional arguments:
  target                a file name

optional arguments:
  -h, --help            show this help message and exit
  --hello HELLO         a string
  -j JAPANESE, --japanese JAPANESE
  --natural NATURAL
  -r REAL, --rea REAL   a real number
  -v                    verbosity flag
  -w