argparse subcommands with nested namespaces

argparse subcommands with nested namespaces

Does argparse provide built-in facilities for having it parse groups or
parsers into their own namespaces? I feel like I must be missing an option
somewhere.
Example:
import argparse
# Main parser
main_parser = argparse.ArgumentParser()
main_parser.add_argument("-common")
# filter parser
filter_parser = argparse.ArgumentParser(add_help=False)
filter_parser.add_argument("-filter1")
filter_parser.add_argument("-filter2")
# sub commands
subparsers = main_parser.add_subparsers(help='sub-command help')
parser_a = subparsers.add_parser('command_a', help="command_a help",
parents=[filter_parser])
parser_a.add_argument("-foo")
parser_a.add_argument("-bar")
parser_b = subparsers.add_parser('command_b', help="command_b help",
parents=[filter_parser])
parser_b.add_argument("-biz")
parser_b.add_argument("-baz")
# parse
namespace = main_parser.parse_args()
print namespace
This is what I get, obviously:
$ python test.py command_a -foo bar -filter1 val
Namespace(bar=None, common=None, filter1='val', filter2=None, foo='bar')
But this is what I am really after:
Namespace(bar=None, common=None, foo='bar',
filter=Namespace(filter1='val', filter2=None))
I've found a related question here but it involves some custom parsing and
seems to only covers a really specific circumstance.
Is there an option somewhere to tell argparse to parse certain groups into
namespaced fields?