I would like to develop a command-line program that can process and give "help" for subcommands. To be concrete, say I have a single script called "cgent" and I would like to have subcommands "abc", "def", and "xyz" execute and accept the rest of the sys.args for processing by optparse.

cgent abc [options]
cgent help abc
....

All of this is straightforward if I hard-code the subcommand names. However, I would like to be able to continue to add subcommands by adding a class or module (?). This is similar to the idea that is used by web frameworks for adding controllers, for example. I have tried digging through pylons to see if I can recreate what is done there, but I have not unravelled the logic. Any suggestions on how to do this?

Thanks, Sean

You'll have to create a "command registry". This can be as simple as a dictionary.

In the main program you do:

commands = {}

And in any submodules you add you do

from yourmodule.main import commands

def mynewcommand(arguments=here):
    pass

commands['newcommand'] = mynewcommand

Then you can use argparse to handle the commands. In which case your module needs to add the subparser part for the command too.