argparsetree

argparsetree

Package for creating complex command line argument trees using argparse.

Basic Usage

You can create a single command by creating a class extending argparsetree.BaseCommand and overriding the add_arguments and action_methods. For example::

from argparsetree import BaseCommand


class MyCommand(BaseCommand):
    def add_arguments(parser):
        parser.add_arguments('foo', help='Some description of "foo"')

    def action(args):
        print(args.foo)

The parser argument passed to add_arguments is an argparse.ArgumentParser object. Similarly the args parameter passed to the action method is a argparse.Namespace object generated by calling parse_args on the generated argument parser.

Additionally the description property can be set on the command class, this will be used when building the help message.

If a return value other than None is returned from action this will be used as the return code from the run function. If no value is returned (or the value is None) the value is assumed to be 0.

Once you have created your command you can use it by creating a script similar to::

#!/usr/bin/env python
import sys

from mycli import MyCommand


if __name__ == '__main__':
    sys.exit(MyCommand().run())

Nested Usage

Child commands can also be added to a command by specifying the sub_commands property. This is a dictionary that maps command names to command classes. For example::

#!/usr/bin/env python

import sys
from argparsetree import BaseCommand


class CleanFooCommand(BaseCommand):
    description = 'Cleans up the foo object'

    def add_args(self, parser):
        parser.add_argument('target', help='The foo file to clean up')
        parser.add_argument('-y', '--yes', help='Automatic answer yes to prompts', action='store_true')

    def action(self, args):
        # do cleaning
        return 0


class CheckFooCommand(BaseCommand):
    description = 'Checks the integrity of a foo object'

    def add_args(self, parser):
        parser.add_argument('target', help='The foo file to clean up')
        parser.add_argument('-y', '--yes', help='Automatic answer yes to prompts', action='store_true')

    def action(self, args):
        # do cleaning
        return 0


class FooCommand(BaseCommand):
    description = 'Do things with foos'
    sub_commands = {
        'check': CheckFooCommand,
        'clean': CleanFooCommand,
        # more sub commands here
    }


class RootCommand(BaseCommand):
    description = 'My fancy CLI'
    sub_commands = {
        'foo': FooCommand,
        # more sub commands here
    }


if __name__ == '__main__':
    sys.exit(RootCommand().run())

Running ./example.py would give the following output::

usage: My fancy CLI [-h] {foo} ...

positional arguments:
  {foo}
    foo       Do things with foos

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

And running ./example.py foo gives::

usage: Do things with foos [-h] {check,clean} ...

positional arguments:
  {check,clean}
    check        Checks the integrity of a foo object
    clean        Cleans up the foo object

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

An extended help message for each command (and sub-command) can be printed by adding the --help flag, So running ./example.py foo check --help gives::

usage: My fancy CLI foo check [-h] [-y] target

Checks the integrity of a foo object

positional arguments:
  target      The foo file to clean up

optional arguments:
  -h, --help  show this help message and exit
  -y, --yes   Automatic answer yes to prompts