Argparse: Required argument ‘y’ if ‘x’ is present

I have a requirement as follows:

./xyifier --prox --lport lport --rport rport

for the argument prox , I use action=’store_true’ to check if it is present or not. I do not require any of the arguments. But, if –prox is set I require rport and lport as well. Is there an easy way of doing this with argparse without writing custom conditional coding.

More Code:

non_int.add_argument('--prox', action='store_true', help='Flag to turn on proxy')
non_int.add_argument('--lport', type=int, help='Listen Port.')
non_int.add_argument('--rport', type=int, help='Proxy port.')

Answer

No, there isn’t any option in argparse to make mutually inclusive sets of options.

The simplest way to deal with this would be:

if args.prox and (args.lport is None or args.rport is None):
    parser.error("--prox requires --lport and --rport.")

Actually there’s already an open PR with an enhancement proposal : https://github.com/python/cpython/issues/55797