argparse_config 0.4a4

With argparse_config your commandline applications will understand config files automatically, based on the commandline arguments you specify.

Let’s say I’m reimplementing the Mercurial commandline client. I specify the commandline argument processing with argparse, of course:

arg_parser = ArgumentParser('hg')
arg_parser.add_argument('--repository')
sub_parsers = arg_parser.add_subparsers()

merge_parser = sub_parsers.add_parser('merge')
merge_parser.add_argument('--tool')
merge_parser.add_argument('--force', type='store_const', const=True, default=False)

commit_parser = sub_parsers.add_parser('commit')
commit_parser.add_argument('--user')
commit_parser.add_argument('--message')

When I go to use this client, though, I have to keep specifying my --user with every commit, and --tool with every merge. That sucks! What I want is to have my client understand a simple config file format:

[merge]
tool: meld

[commit]
user: Tikitu de Jager <tikitu@logophile.org>

And obviously, as I add more arguments and subcommands to my client, it should allow me to add defaults in the config file without writing more code.

This is what argparse_config gives you. To use it with the mercurial client arg_parser above:

>>> import argparse_config
>>> argparse_config.read_config(arg_parser, '/home/tikitu/.my_hg.cfg')

… and that’s it. Calling arg_parser.parse_args() will parse args as usual, but the default values will be taken from the config file, if they are given there:

>>> parsed_args = arg_parser.parse_args(['merge'])
>>> parsed_args.tool
'meld'

[default]
verbose: