Require either of two arguments using argparse

Question

Given:

import argparse

pa = argparse.ArgumentParser()
pa.add_argument('--foo')
pa.add_argument('--bar')

print pa.parse_args('--foo 1'.split())

how do I

• make at least one of "foo, bar" mandatory: --foo x, --bar y and --foo x --bar y are fine
• make at most one of "foo, bar" mandatory: --foo x or --bar y are fine, --foo x --bar y is not

Answer 1

I think you are searching for something like mutual exclusion (at least for the second part of your question).

This way, only foo or bar will be accepted, not both.

    import argparse

    parser = argparse.ArgumentParser()
    group = parser.add_mutually_exclusive_group(required=True)
    group.add_argument('--foo',action=.....)
    group.add_argument('--bar',action=.....)
    args = parser.parse_args()

BTW, just found another question referring to the same kind of issue.

Hope this helps