python, argparse: enable input parameter when another one has been specified

Question

In my python script, I want to be able to use an optional input parameter only when another optional parameter has been specified. Example:

$ python         


        

Answer 1

One idea would be to manually check the output of calling parser.parse_args() and raise an exception or otherwise fail if --parameter2 is used but --parameter1 isn't.

You could also try setting a custom action (scroll down a bit) to --parameter2 check if --parameter1 exists inside the namespace.

Finally, you could try using subparsers, although I don't know if it'll let you specify a value for --parameter1.