Create Mutual Inclusive arguments with argparse

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

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