Python CLI App

Framework for creating CLI apps using Python

The purpose of this library is to speed up bulding CLI applications by providing abstract classes representing an app and its commands. It uses argparse to define and parse command line arguments.

Concepts

App

An “App” is the main entry point of an application. It groups together one or more commands

Command

A “Command” is a single operation that the application can perform. It is identified by a positional argument on the command line. Let’s take git as an example. git would be the app that provides different commands, such as add, commit, merge, checkout, etc.

Example

git.py

#!/usr/bin/env python3
from cli_app import App
from commands.checkout import Checkout
from commands.merge import Merge
class Git(App):
    """Git - fast, scalable, distributed revision control system"""
    def register_commands(self):
        self.add_command('checkout', Checkout)  # make the Checkout command available through `git.py checkout …`
        self.add_command('merge', Merge)  # make the Merge command available through `git.py merge …`
if __name__ == '__main__':
    app = Git()
    app.run()

commands/checkout.py

from cli_app import Command
class Checkout(Command):
    """Switch branches or restore working tree files"""
    @staticmethod
    def register_arguments(parser):
        parser.add_argument('ref', type=str, help='The ref (branch name, tag, commit sha) to checkout')
    def run(self):
        # Do whatever needs to be done to checkout given ref
        print('Checking out %s' % self.app.args.ref)

commands/merge.py

from cli_app import Command
class Merge(Command):
    """Join two or more development histories together"""
    @staticmethod
    def register_arguments(parser):
        parser.add_argument('branch', type=str, help='The branch to merge into the currently checked-out branch')
    def run(self):
        # Do whatever needs to be done to merge given branch
        print('Merging %s into current branch' % self.app.args.branch)