argh / README

Argh: The Natural CLI

Building a command-line interface?  Found yourself uttering "argh!" while
struggling with the API of `argparse`?  Don't want to lose its power but don't
need the complexity?

.. epigraph::

    Everything should be made as simple as possible, but no simpler.

    -- Albert Einstein (probably)

`Argh` provides a wrapper for `argparse`.  `Argparse` is a very powerful tool;
`Argh` just makes it easy to use.

In a nutshell

`Argh`-powered applications are *simple* but *flexible*:

    Declaration of commands can be decoupled from assembling and dispatching;

    Commands are declared naturally, no complex API calls in most cases;

    Commands are plain functions, can be used directly outside of CLI context;

    The complexity of code raises with requirements;

    The full power of argparse is available whenever needed;

    Nested commands are a piece of cake, no messing with subparsers (though
    they are of course used under the hood);

    Command output is processed with respect to stream encoding;

    `Argh` can dispatch a subset of pure-`argparse` code, and pure-`argparse`
    code can update and dispatch a parser assembled with `Argh`;

    The amount of boilerplate code is minimal; among other things, `Argh` will:

    * infer command name from function name;
    * infer arguments from function signature;
    * infer argument type from the default value;
    * infer argument action from the default value (for booleans);
    * add an alias root command ``help`` for the ``--help`` argument.

Sounds good?  Check the tutorial!

Relation to argparse

`Argh` is fully compatible with `argparse`.  You can mix `Argh`-agnostic and
`Argh`-aware code.  Just keep in mind that the dispatcher does some extra work
that a custom dispatcher may not do.


Using pip::

    $ pip install argh

Arch Linux (AUR)::

    $ yaourt python-argh


A very simple application with one command:

.. code-block:: python

    import argh

    def main():
        return 'Hello world'


A potentially modular application with multiple commands:

.. code-block:: python

    import argh

    # declaring:

    def echo(text):
        return text

    def greeter(name, greeting='hello'):
        return greeting + ', ' + name

    # assembling:

    parser = argh.ArghParser()
    parser.add_commands([echo, greeter])

    # dispatching:

    if __name__ == '__main__':

The powerful API of `argparse` is also available:

.. code-block:: python

    @arg('text', default='hello world', nargs='+', help='The message')
    def echo(text):
        print text

The approaches can be safely combined even up to this level:

.. code-block:: python

    # adding help to `foo` which is in the function signature:
    @arg('foo', help='blah')
    # these are not in the signature so they go to **kwargs:
    @arg('-q', '--quux')
    # the function itself:
    def cmd(foo, bar=1, *args, **kwargs):
        yield foo
        yield bar
        yield ', '.join(args)
        yield kwargs['baz']
        yield kwargs['quux']


* `Project home page`_ (Bitbucket)
* `Documentation`_ (Read the Docs)
* `Package distribution`_ (PyPI)
* Questions, requests, bug reports, etc.:

  * `Issue tracker`_
  * `Mailing list`_ (subscribe to get important announcements)
  * Direct e-mail (neithere at gmail com)
  * Twitter_ (to get notified of commits; mostly for lulz)

.. _project home page:
.. _documentation:
.. _package distribution:
.. _issue tracker:
.. _mailing list:
.. _twitter:


Developed by Andrey Mikhaylenko since 2010.

See file `AUTHORS` for a complete list of contributors to this library.


Argh is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Argh is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with Argh.  If not, see <>.