Python Argparse conditionally required arguments

Question

I have done as much research as possible but I haven\'t found the best way to make certain cmdline arguments necessary only under certain conditions, in this case only if ot

Answer 1

This is really the same as @Mira 's answer but I wanted to show it for the case where when an option is given that an extra arg is required:

For instance, if --option foo is given then some args are also required that are not required if --option bar is given:

if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument('--option', required=True,
        help='foo and bar need different args')

    if 'foo' in sys.argv:
        parser.add_argument('--foo_opt1', required=True,
           help='--option foo requires "--foo_opt1"')
        parser.add_argument('--foo_opt2', required=True,
           help='--option foo requires "--foo_opt2"')
        ...

    if 'bar' in sys.argv:
        parser.add_argument('--bar_opt', required=True,
           help='--option bar requires "--bar_opt"')
        ...

It's not perfect - for instance proggy --option foo --foo_opt1 bar is ambiguous but for what I needed to do its ok.