argparse - How to handle parent parser behaviour?

Question

I have a parent parser which defines a common flag --global which is globally available across subparsers.

     parent (defines --global)
    /      \
child1      child2
--global    --global

I am handling the flags of child1 and child2 via set_dfault. Since both subparsers inherit --global I have to handle the flag in both subparser functions. How can I improve this? Can I define the behaviour of --global in parent once without repeating me?

parent = argparse.ArgumentParser(add_help=False)
parent.add_argument("--global", action="store_true")

def handle_child1(xargs):
    if xargs.global:
        print("handle global")
    print("do stuff from child 1")
        

def handle_child2(yargs):
    if yargs.global:
        print("handle global")
    print("do stuff from child 2")

subparser = parser.add_subparsers()
child1 = subparser.add_parser("c1", parents=[parent])
subparse_x.set_defaults(func=handle_child1)

child2 = subparser.add_parser("c2", parents=[parent])
subparse_y.set_defaults(func=handle_child2)

As you can see I have to handle global in each subparser. Not idea. Of cause I could call a function handle_global from each subparser to make this a bit better. However is there a solution that just lets parent handle global?

Answer 1

If I understand what you are attempting to do you can handle the global attribute prior to sending the arguments to the correct sub-command function.

import argparse

def handle_global_flag():
    print("handling --global")

def handle_child1(args):
    print(args)
    print("do stuff from child 1")

def handle_child2(args):
    print(args)
    print("do stuff from child 2")

parent = argparse.ArgumentParser(add_help=False)
parent.add_argument("--global", action="store_true")

parser = argparse.ArgumentParser(add_help=False)
subparsers = parser.add_subparsers(dest="command")

child1 = subparsers.add_parser("c1", parents=[parent])
child1.set_defaults(func=handle_child1)

child2 = subparsers.add_parser("c2", parents=[parent])
child2.set_defaults(func=handle_child2)

args = parser.parse_args()

if args.command is not None:
    if getattr(args, "global"):
        handle_global_flag()
    args.func(args)
else:
    parser.print_help()
    parser.exit()