arseparse 0.1.2
Command-line app helper library
License: MIT
Keywords: cli,argparse,command-line

Arseparse
=========

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Arseparse is a simple Python utility/micro framework for writing command
line interfaces. It provides some functionality around `argparse`_ that
covers some common scenarios.

Installation:

::

    pip install arseparse

Basic usage:

::

    from arseparse import Parser, Option


    parser = Parser()


    # register a command that returns the square of an int
    parser.register('square', lambda value: value**2, [Option('value', type=int)])


    # register a command that simply returns a string
    parser.register('ping', lambda: 'pong')


    # or with a decorator
    @parser.register_dec([Option('value', type=int)])
    def cube(value):
        return value**3


    sys.exit(parser.run())

You can then point an application entrypoint to the script or execute
the file: ``your-entrypoint.py square 2``

So far so boring. A more common scenario is to have a config file as the
first argument, parse it, create objects that the command depends on,
and pass those alongside the parsed attributes. The ``root_options`` and
``bootstrap`` constructor args to ``Parser`` allow us to implement this:

::

    from arseparse import Parser, Option
    import myapp


    # these are options that come before our main command
    root_options = [Option('config', type=str, help='path to ini file')]


    # this lets us process/modify the kwargs before we execute the callable.
    # we can rely on attributes resulting from root_options to be set.
    # here config gets replaced by three objects: settings, db_session and user_svc
    def bootstrap(**kwargs):
        config_uri = kwargs.pop('config')
        settings = myapp.parse_app_config(config_uri)
        dbsession = myapp.get_sessionmaker(settings)()
        user_svc = myapp.UserService(dbsession)
        kwargs.update(dict(settings=settings, dbsession=dbsession, user_svc=user_svc))
        return kwargs


    parser = Parser(root_options, bootstrap)


    @parser.register_dec([Option('username', type=str), Option('secret', type=str)])
    def create_user(username, secret, user_svc, **kwargs):
        user_svc.create_user(username, secret)
        
     
    @parser.register_dec([Option('user_id', type=int)])
    def ban_user(user_id, user_svc, **kwargs):
        user_svc.ban_user(user_id)


    @parser.register_dec()
    def print_settings(settings, **kwargs):
        print(settings)

You can now provide the path to a config file as the first argument:
``your-entrypoint.py config.ini ban_user 23``

Another common requirement is to be able to jump into a shell where some
objects have been preconfigured for us. Here’s a simple recipe for that:

::

    @parser.register_dec()
    def shell(**kwargs):
        import IPython
        IPython.embed(user_ns=kwargs)


Calling `your-entrypoint.py config.ini shell` will drop you in an ipython shell where `dbsession`, `settings` and `user_svc` are in scope.

.. _argparse: https://docs.python.org/3/library/argparse.html

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