How to make python argparse mutually exclusive group arguments without prefix?

Question

Python2.7 argparse only accepts optional arguments (prefixed) in mutually exclusive groups:

parser = argparse.ArgumentParser(prog='mydaemon')
action = parser.add_mutually_exclusive_group(required=True)
action.add_argument('--start', action='store_true', help='Starts %(prog)s daemon')
action.add_argument('--stop', action='store_true', help='Stops %(prog)s daemon')
action.add_argument('--restart', action='store_true', help='Restarts %(prog)s daemon')

$ mydaemon -h

usage: mydaemon [-h] (--start | --stop | --restart)

optional arguments:
  -h, --help  show this help message and exit
  --start     Starts mydaemon daemon
  --stop      Stops mydaemon daemon
  --restart   Restarts mydaemon daemon

Is there a way to make argparse arguments behaves like traditional unix daemon control:

(start | stop | restart) and not (--start | --stop | --restart) ?

Answer 1

from pymotw

import argparse

parser = argparse.ArgumentParser()

group = parser.add_mutually_exclusive_group()
group.add_argument('-a', action='store_true')
group.add_argument('-b', action='store_true')

print parser.parse_args()

output:

$ python argparse_mutually_exclusive.py -h  
usage: argparse_mutually_exclusive.py [-h] [-a | -b]

optional arguments:  
  -h, --help  show this help message and exit  
  -a  
  -b  

$ python argparse_mutually_exclusive.py -a  
Namespace(a=True, b=False)

$ python argparse_mutually_exclusive.py -b  
Namespace(a=False, b=True)

$ python argparse_mutually_exclusive.py -a -b  
usage: argparse_mutually_exclusive.py [-h] [-a | -b]  
argparse_mutually_exclusive.py: error: argument -b: not allowed with argument -a

version2

import argparse

parser = argparse.ArgumentParser()

subparsers = parser.add_subparsers(help='commands')

# A list command
list_parser = subparsers.add_parser('list', help='List contents')
list_parser.add_argument('dirname', action='store', help='Directory to list')

# A create command
create_parser = subparsers.add_parser('create', help='Create a directory')
create_parser.add_argument('dirname', action='store', help='New directory to create')
create_parser.add_argument('--read-only', default=False, action='store_true',
                       help='Set permissions to prevent writing to the directory',
                       )

# A delete command
delete_parser = subparsers.add_parser('delete', help='Remove a directory')
delete_parser.add_argument('dirname', action='store', help='The directory to remove')
delete_parser.add_argument('--recursive', '-r', default=False, action='store_true',
                       help='Remove the contents of the directory, too',
                       )

print parser.parse_args(['list', 'a s d', ])
>>> Namespace(dirname='a s d')
print parser.parse_args(['list', 'a s d', 'create' ])
>>> error: unrecognized arguments: create