Python argparse prevent long and short flags at same time

Question

I have this code:

parser = argparse.ArgumentParser()
parser.add_argument('-L', '--list', action='store_true', help='list options')
args = parser.parse_args()

I want this:

$./example.py --list

or

$./example.py -L

but not:

$./example -L --list # or --list -L

Is there an elegant way to avoid that both flags being used at the same time?

Answer 1

You can form a mutually exclusive group. That isn't ideal, since you'll end up repeating arguments to each, but that can be wrapped up into a helper function if need be.

parser = argparse.ArgumentParser()

arg_group = parser.add_mutually_exclusive_group()
arg_group.add_argument('-L', action='store_true', help='list options')
arg_group.add_argument('--list', action='store_true', help='list options')

args = parser.parse_args()

If you wanted to pretty this up a bit (to avoid repeating yourself), you could do something like:

class MutexArgParser(argparse.ArgumentParser):
    def add_mutex_arguments(self, flags, *args, **kwargs):
        arg_group = self.add_mutually_exclusive_group()
        for flag in flags:
            arg_group.add_argument(flag, *args, **kwargs)

parser = MutexArgParser()
parser.add_mutex_arguments(['-L', '--list'], action='store_true', help='list options')
args = parser.parse_args()