python argparse choices with a default choice

Pass the nargs and const arguments to add_argument:

parser.add_argument('--list',                    default='all',                    const='all',                    nargs='?',                    choices=['servers', 'storage', 'all'],                    help='list servers, storage, or both (default: %(default)s)')

If you want to know if --list was passed without an argument, remove the const argument, and check if args.list is None.

Thanks @ShadowRanger. Subcommands is exactly what I need, combined with nargs and const. The following works:

parser = argparse.ArgumentParser()subparser = parser.add_subparsers()parser_list = subparser.add_parser('list')parser_list.add_argument('list_type', default='all', const='all', nargs='?', choices=['all', 'servers', 'storage'])parser_create = subparser.add_parser('create')parser_create.add_argument('create_type', default='server', const='server', nargs='?', choices=['server', 'storage'])args = parser.parse_args()pprint(vars(args))$ python3 ./myapp.py -husage: dotool.py [-h] {list,create} ...Digital Ocean toolpositional arguments:  {list,create}optional arguments:  -h, --help     show this help message and exit

list option alone:

$ python3 ./myapp.py list{'list_type': 'all'}

List option with a parameter:

$ python3 ./myapp.py list servers{'list_type': 'servers'}