parser.py 文件源码

def required_length(minimum: int, maximum: int, optional: bool = False):
    """Returns a custom required length class"""

    class RequiredLength(argparse.Action):
        def __call__(self, parser, args, values, option_string=None):
            is_allowed = (
                (minimum <= len(values) <= maximum) or
                (optional and not len(values))
            )

            if  is_allowed:
                setattr(args, self.dest, values)
                return

            raise argparse.ArgumentTypeError(
                'Argument "{}" must have {}-{} arguments'.format(
                    self.dest,
                    minimum,
                    maximum
                )
            )

    return RequiredLength