A snippet that make Python package integrate argument parsers of its sub packages

__main__.py

# file path: `mod/__main__.py`

import argparse, importlib, inspect, sys

prog = sys.argv[0]
if prog.endswith('__main__.py'):
    prog = f'python -m {__package__}'
else:
    prog = prog.rsplit('/',1)[-1]

parser = argparse.ArgumentParser(prog=prog, description='A toolbox collecting features')
subparsers = parser.add_subparsers(metavar='{subcommand}', dest='subcommand', required=True)
submains = {}
for alias, modpath in [('tool_1', '.feature')]:
    mod = importlib.import_module(modpath, __package__)
    desc = inspect.signature(mod.parse_args).parameters['parser'].default.description
    subparser = subparsers.add_parser(alias, description=desc, help=desc)
    subparser.parse_args = lambda:None
    mod.parse_args(subparser)
    submains[alias] = mod.main

args = parser.parse_args()
main = submains[args.subcommand]
main(args)

console.md

$ toolbox
usage: toolbox [-h] {subcommand} ...
toolbox: error: the following arguments are required: {subcommand}
$ python -m mod
usage: python -m mod [-h] {subcommand} ...
python -m mod: error: the following arguments are required: {subcommand}

$ toolbox -h
usage: toolbox [-h] {subcommand} ...

A toolbox collecting features

positional arguments:
  {subcommand}
    tool_1      A feature helping to do something

optional arguments:
  -h, --help    show this help message and exit
$ python -m mod -h
usage: python -m mod [-h] {subcommand} ...

A toolbox collecting features

positional arguments:
  {subcommand}
    tool_1      A feature helping to do something

optional arguments:
  -h, --help    show this help message and exit

$ toolbox tool_1 -h
usage: toolbox tool_1 [-h] arg

A feature helping to do something

positional arguments:
  arg         arg for the feature

optional arguments:
  -h, --help  show this help message and exit
$ python -m mod tool_1 -h
usage: python -m mod tool_1 [-h] arg

A feature helping to do something

positional arguments:
  arg         arg for the feature

optional arguments:
  -h, --help  show this help message and exit
$ python -m mod.feature -h
usage: python -m mod.feature [-h] arg

A feature helping to do something

positional arguments:
  arg         arg for the feature

optional arguments:
  -h, --help  show this help message and exit

$ toolbox tool_1 arg
start running with args: Namespace(subcommand='tool_1', arg='arg')
$ python -m mod tool_1 arg
start running with args: Namespace(subcommand='tool_1', arg='arg')
$ python -m mod.feature arg
start running with args: Namespace(arg='arg')

feature.py

# file path: `mod/feature.py`

def parse_args(parser=__import__('argparse').ArgumentParser(
    prog=f'python -m {__package__}.{__file__.rsplit("/",1)[-1].split(".")[0]}',
    description='A feature helping to do something',
    )):
    parser.add_argument('arg', help='arg for the feature')
    return parser.parse_args()


def main(args):
    print(f'start running with args: {args}')


if __name__ == '__main__':
    main(parse_args())

toolbox

#!/usr/bin/env python

# Writing it in shell script like below is improper because of
# unable to get called name::
#
#   #!/bin/sh
#   python -m mod "$@"
#
# Instead, make command itself to be a Python script.

# Run main of `mod`
from mod import __main__