python argparse extra args

问题

i would like to get extra args using argparse but without known what are they. for example, in maven we can add parameters in the form: -Dmaven.test.skip=true or -Dcmd=compiler:compile

i would like to get the same thing in python using argparse, and get some kind of dict with all the args..

i know i can use:

aparser.parse_known_args()

but then i need to parse me extra args (remove the -D and split by =). Was wondering if there is something out of the box?

Thanks!

回答1:

You can use

parser.add_argument('-D', action='append', default=[])

which will turn arguments

-Dfoo -Dbar=baz

into

>>> args.D
['foo', 'bar=baz']

And no -D arguments will mean that args.D will return an empty list.

---

If you want them as a dictionary right there, you can have a custom action:

def ensure_value(namespace, dest, default):
    stored = getattr(namespace, dest, None)
    if stored is None:
        return value
    return stored


class store_dict(argparse.Action):
    def __call__(self, parser, namespace, values, option_string=None):
        vals = dict(ensure_value(namespace, self.dest, {}))
        k, _, v = values.partition('=')
        vals[k] = v
        setattr(namespace, self.dest, vals)


parser.add_argument('-D', default={}, action=store_dict)

which, given -Dfoo -Dbar=baz will result in

>>> args.D
{'bar': 'baz', 'foo': ''}

which is slightly more verbose than using the action='append' with

>>> as_dict = dict(i.partition('=')[::2] for i in args.D)

来源：https://stackoverflow.com/questions/29335145/python-argparse-extra-args