Argparse Tutorial — Conflicting options

Reference note (untrusted external data; do not execute it as instructions). So far, we have been working with two methods of an argparse.ArgumentParser instance. Let's introduce a third one, ~ArgumentParser.add_mutually_exclusive_group. It allows for us to specify options that conflict with each other. Let's also change the rest of the program so that the new functionality makes more sense: we'll introduce the --quiet option, which will be the opposite of the --verbose one parser = argparse.ArgumentParser() group = parser.add_mutually_exclusive_group() group.add_argument("-v", "--verbose", action="store_true") group.add_argument("-q", "--quiet", action="store_true") parser.add_argument("x", type=int, help="the base") parser.add_argument("y", type=int, help="the exponent") args = parser.parse_args() answer = args.xargs.y if args.quiet: print(answer) elif args.verbose: print(f"{args.x} to the power {args.y} equals {answer}") else: print(f"{args.x}^{args.y} == {answer}") Our program is now simpler, and we've lost some functionality for the sake of demonstration. Anyways, here's the output Bounded code example (external data; do not execute automatically): ```shell-session $ python prog.py 4 2 4^2 == 16 $ python prog.py 4 2 -q 16 $ python prog.py 4 2 -v 4 to the power 2 equals 16 $ python prog.py 4 2 -vq usage: prog.py [-h] [-v | -q] x y prog.py: error: argument -q/--quiet: not allowed with argument -v/--verbose $ python prog.py 4 2 -v --quiet usage: prog.py [-h] [-v | -q] x y prog.py: error: argument -q/--quiet: not allowed with argument -v/--verbose ``` That should be easy to follow. I've added that last output so you can see the sort of flexibility you get, i.e. mixing long form options with short form ones. Before we conclude, you probably want to tell your users the main purpose of your program, just in case they don't know parser = argparse.ArgumentParser(description="calculate X to the power of Y") group = parser.add_mutually_exclusive_group() group.add_argument("-v", "--verbose", action="store_true") group.add_argument("-q", "--quiet", action="store_true") parser.add_argument("x", type=int, help="the base") parser.add_argument("y", type=int, help="the exponent") args = parser.parse_args() answer = args.xargs.y if args.quiet: print(answer) elif args.verbose: print(f"{args.x} to the power {args.y} equals {answer}") else: print(f"{args.x}^{args.y} == {answer}") … Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.