nested subparsers with argparse

[Chris Withers]

Chris Withers wrote:
> Hi All,
> 
> I'm looking to build a script that has command line options as follows:
> 
> ./myscript.py command subcommand [options]
> 
> I can do up to the command [options] bit with add_subparsers in 
> argparse, but how do I then add a second level of subparsers?

Answering my own question, here's what worked for me:

"""
from argparse import ArgumentParser
from mock import Mock

m = Mock()

parser = ArgumentParser()
subparsers = parser.add_subparsers()

agroup = subparsers.add_parser('a')

command = subparsers.add_parser('b')
command.set_defaults(func=m.b)

subparsers = agroup.add_subparsers()
command = subparsers.add_parser('aa')
command.set_defaults(func=m.a.a)

command = subparsers.add_parser('ab')
command.set_defaults(func=m.a.b)

options = parser.parse_args()

options.func(options)

print m.method_calls
"""

If there's anything I could have done better, please let me know!

Chris