Building a CLI with subparsers from separate modules

bar.py

def build_subparser(subparsers):
    """
    Build subparser for this command
    """
    parser = subparsers.add_parser('bar', help='foo help')
    parser.add_argument('b', type=int, help='b help')
    parser.set_defaults(func=main)


def main(args):
    """
    Main routine for bar
    """
    print args.b

foo.py

def build_subparser(subparsers):
    """
    Build subparser for this command
    """
    parser = subparsers.add_parser('foo', help='foo help')
    parser.add_argument('a', type=int, help='a help')
    parser.set_defaults(func=main)


def main(args):
    """
    Main routine for foo
    """
    print args.a

tool.py

#!/usr/bin/env python
#-*- coding:utf-8 -*-
"""
Sandbox example of CLI subparsers built from separate modules
"""
import foo
import bar

if __name__ == '__main__':
    
    import argparse
    
    parser = argparse.ArgumentParser(description=__doc__)
    subparsers = parser.add_subparsers(help='sub-command help')
    
    foo.build_subparser(subparsers)
    bar.build_subparser(subparsers)
    
    args = parser.parse_args()
    
    args.func(args)