CmdKit
======

Release v\ |release|. (:ref:`Tutorial <tutorial>`)

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    :alt: License

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The *cmdkit* library implements a few common patterns needed by well-formed command-line
applications in Python. It only touches a few concepts but it implements them well.
The idea is to reduce the boilerplate needed to get a full featured CLI off the ground.
Applications developed using *cmdkit* are easy to implement, easy to maintain, and easy to
understand.

-------------------

Features
--------

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An :class:`~cmdkit.app.Application` class provides the boilerplate for a good entry-point.
Building your command-line application in layers with :class:`~cmdkit.app.ApplicationGroup`
let's you develop simple structures and modules that mirror your CLI.

An :class:`~cmdkit.cli.Interface` class modifies the behavior of the standard
:class:`argparse.ArgumentParser` class to raise simple exceptions instead of exiting.

.. code-block:: python

    class Add(Application):
        """Application class for simple adding program."""

        interface = Interface('add', USAGE_TEXT, HELP_TEXT)
        interface.add_argument('-v', '--version', action='version', version='0.0.1')

        lhs: float
        rhs: float
        interface.add_argument('lhs', type=float)
        interface.add_argument('rhs', type=float)

        def run(self) -> None:
            """Business logic of the application."""
            print(self.lhs + self.rhs)


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A :class:`~cmdkit.config.Configuration` class makes it basically a one-liner to pull in
a configuration with a dictionary-like interface from a cascade of files as well as
expanding environment variables into a hierarchy and merged.

The standard behavior for any `good` application is for a configuration to allow for
system-level, user-level, and local configuration to overlap. Merging these should not
clobber the same section in a lower-priority source. The :class:`~cmdkit.config.Namespace`
class extends the behavior of a standard Python `dict` to have a depth-first merge for its
`update` implementation.

.. code-block:: python

    config = Configuration.from_local(env=True, prefix='MYAPP', default=default, **paths)

The underlying :class:`~cmdkit.config.Namespace` also supports the convention of having
parameters with ``_env`` and ``_eval`` automatically expanded.

.. code-block:: toml
    :caption: ~/.myapp/config.toml

    [database]
    password_eval = "gpg ..."

Accessing the parameter with dot-notation, i.e., ``config.database.password`` would execute
``"gpg ..."`` as a shell command and return the output.

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-------------------

Installation
------------

*CmdKit* is tested on Python 3.7+ for `Windows`, `macOS`, and `Linux`, and can be installed
from the `Python Package Index` using `Pip`.

::

    $ pip install cmdkit

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-------------------

Getting Started
---------------

Checkout the :ref:`Tutorial <tutorial>` for examples.

You can also checkout how `CmdKit` is being used by other projects.

========================================================  =======================================================
Project                                                   Description
========================================================  =======================================================
`REFITT <https://github.com/refitt/refitt>`_              Recommender Engine for Intelligent Transient Tracking
`hyper-shell <https://github.com/glentner/hyper-shell>`_  Hyper-shell is an elegant, cross-platform, high-performance
                                                          computing utility for processing shell commands over a
                                                          distributed, asynchronous queue.
`delete-cli <https://github.com/glentner/delete-cli>`_    A simple, cross-platform, command-line move-to-trash.
========================================================  =======================================================


-------------------

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**Table of Contents**

.. toctree::

    api/index
    tutorial/index
    blog/index
    contributing
    license