Create Mutual Inclusive arguments with argparse

Question

I want to build a program that has 2 mutually inclusive args and 2 that are not dependent on the first two. Something like this:

consume [--count n] | show | clear

where 'consume' and '--count' are dependent on each other i.e, without 'consume' '--count' will throw an error 'show' and 'clear' do not depend on the first consume and --count.

Edit: show and clear are optional arguments

Here's what I was able to do till now:

import argparse
parser = argparse.ArgumentParser()
group = argparse.ArgumentParser(usage='%(prog)s [consume [--count]]')
group.add_argument('consume', help='mutually inclusive with count')
group.add_argument('--count', type = int, help='get the count n')

parser.add_argument('show', help='show the messages')
parser.add_argument('clear', help='clear messages from db')

args = group.parse_args()
args1 = parser.parse_args()

if args.count and not args.consume:
    parser.error('the following arguments are required: consume')
else:
    print(args.count)
    print(args1.show)
    print(args1.clear)

So when the run the command, without consume:

[filename] --count 7 show clear

I get the following error:

unrecognized arguments: clear

Can someone help me with making the arguments mutually inclusive and other arguments not dependent on them?

Answer 1

You could try something like this...

Add a MutuallyInclusiveArgumentError Exception subclass, then split the arguments in an argument group, and check for errors after parsing has been completed.

import argparse
import sys
class MutuallyInclusiveArgumentError(Exception):
    pass

parser = argparse.ArgumentParser(sys.argv[0])
subs = parser.add_argument_group("mutually inclusive")
subs.add_argument('--consume', help='mutually inclusive with count', action='store_true')
subs.add_argument('--count', type = int, help='get the count n')
parser.add_argument('--show', help='show the messages', action='store_true')
parser.add_argument('--clear', help='clear messages from db', action='store_true')


args = parser.parse_args()
if args.count and args.consume is False:
    raise MutuallyInclusiveArgumentError("--count option must be used with the --consume option" )



print(vars(args))

the help message looks like this

usage: {progname} [-h] [--consume] [--count COUNT] [--show] [--clear]

options:
  -h, --help     show this help message and exit
  --show         show the messages
  --clear        clear messages from db

mutually inclusive:
  --consume      mutually inclusive with count
  --count COUNT  get the count n