argparse with --no-flag options

argparse-no-flags.py

import argparse

class ActionFlagWithNo(argparse.Action):
    """
        Allows a 'no' prefix to disable store_true actions.
        For example, --debug will have an additional --no-debug to explicitly disable it.
    """
    def __init__(self, opt_name, dest=None, default=True, required=False, help=None):
        super(ActionFlagWithNo, self).__init__(
            [
                '--' + opt_name[0],
                '--no-' + opt_name[0],
            ] + opt_name[1:],
            dest=(opt_name[0].replace('-', '_') if dest is None else dest),
            nargs=0, const=None, default=default, required=required, help=help,
        )

    def __call__(self, parser, namespace, values, option_string=None):
        if option_string.startswith('--no-'):
            setattr(namespace, self.dest, False)
        else:
            setattr(namespace, self.dest, True)

class ActionFlagWithNoFormatter(argparse.HelpFormatter):
    """
        This changes the --help output, what is originally this:

            --file, --no-file, -f

        Will be condensed like this:

            --[no-]file, -f
    """

    def _format_action_invocation(self, action):
        if action.option_strings[1].startswith('--no-'):
            return ', '.join(
                [action.option_strings[0][:2] + '[no-]' + action.option_strings[0][2:]]
                + action.option_strings[2:]
            )
        return super(ActionFlagWithNoFormatter, self)._format_action_invocation(action)


def main(argp=None):
    if argp is None:
        argp = argparse.ArgumentParser(
            formatter_class=ActionFlagWithNoFormatter,
        )
        argp._add_action(ActionFlagWithNo(['flaga', '-a'], default=False, help='...'))
        argp._add_action(ActionFlagWithNo(['flabb', '-b'], default=False, help='...'))

        argp = argp.parse_args()

if __name__ == '__main__':
    main()