Question

Is there a Python module for doing gem/git-style command line arguments? What I mean by gem/git style is:

$ ./MyApp.py
The most commonly used MyApp commands are:
  add        Add file contents to the index
  bisect     Find by binary search the change that introduced a bug
  branch     List, create, or delete branches
  checkout   Checkout a branch or paths to the working tree
  ...

$ ./MyApp.py branch
  * current-branch
    master

With no arguments, the output tells you how you can proceed. And there is a special “help” command:

$ ./MyApp.py help branch

Which gets you deeper tips about the “branch” command.

Edit:
And by doing I mean it does the usage printing for you, exits with invalid input, runs your functions according to your CLI specification. Sort of a “URL mapper” for the command line.

Answer 1

Yes, argparse with add_subparsers().

It’s all well explained in the Sub-commands section.

Copying one of the examples from there:

>>> parser = argparse.ArgumentParser()
>>> subparsers = parser.add_subparsers()
>>> checkout = subparsers.add_parser('checkout', aliases=['co'])
>>> checkout.add_argument('foo')
>>> parser.parse_args(['checkout', 'bar'])
Namespace(foo='bar')

Edit: Unfortunately there’s no self generated special help command, but you can get the verbose help message (that you seem to want) with -h or --help like one normally would after the command:

$ ./MyApp.py branch --help

By verbose I don’t mean that is like a man page, it’s like every other --help kind of help: listing all the arguments, etc…

Example:

>>> parser = argparse.ArgumentParser()
>>> subparsers = parser.add_subparsers(description='Sub description')
>>> checkout = subparsers.add_parser('checkout', description='Checkout description')
>>> checkout.add_argument('foo', help='This is the foo help')
>>> parser.parse_args(['checkout', '--help'])
usage:  checkout [-h] foo

Checkout description

positional arguments:
  foo         This is the foo help

optional arguments:
  -h, --help  show this help message and exit

If you need to, it should be easy to implement an help command that redirects to --help.