Distributing Python Modules
***************************

Email:
   distutils-sig@python.org

As a popular open source development project, Python has an active
supporting community of contributors and users that also make their
software available for other Python developers to use under open
source license terms.

This allows Python users to share and collaborate effectively,
benefiting from the solutions others have already created to common
(and sometimes even rare!) problems, as well as potentially
contributing their own solutions to the common pool.

This guide covers the distribution part of the process. For a guide to
installing other Python projects, refer to the installation guide.

Note:

  For corporate and other institutional users, be aware that many
  organisations have their own policies around using and contributing
  to open source software. Please take such policies into account when
  making use of the distribution and installation tools provided with
  Python.


Key terms
=========

* the Python Package Index is a public repository of open source
  licensed packages made available for use by other Python users

* the Python Packaging Authority are the group of developers and
  documentation authors responsible for the maintenance and evolution
  of the standard packaging tools and the associated metadata and file
  format standards. They maintain a variety of tools, documentation
  and issue trackers on both GitHub and Bitbucket.

* "distutils" is the original build and distribution system first
  added to the Python standard library in 1998. While direct use of
  "distutils" is being phased out, it still laid the foundation for
  the current packaging and distribution infrastructure, and it not
  only remains part of the standard library, but its name lives on in
  other ways (such as the name of the mailing list used to coordinate
  Python packaging standards development).

* setuptools is a (largely) drop-in replacement for "distutils" first
  published in 2004. Its most notable addition over the unmodified
  "distutils" tools was the ability to declare dependencies on other
  packages. It is currently recommended as a more regularly updated
  alternative to "distutils" that offers consistent support for more
  recent packaging standards across a wide range of Python versions.

* wheel (in this context) is a project that adds the "bdist_wheel"
  command to "distutils"/setuptools. This produces a cross platform
  binary packaging format (called “wheels” or “wheel files” and
  defined in **PEP 427**) that allows Python libraries, even those
  including binary extensions, to be installed on a system without
  needing to be built locally.


Open source licensing and collaboration
=======================================

In most parts of the world, software is automatically covered by
copyright. This means that other developers require explicit
permission to copy, use, modify and redistribute the software.

Open source licensing is a way of explicitly granting such permission
in a relatively consistent way, allowing developers to share and
collaborate efficiently by making common solutions to various problems
freely available. This leaves many developers free to spend more time
focusing on the problems that are relatively unique to their specific
situation.

The distribution tools provided with Python are designed to make it
reasonably straightforward for developers to make their own
contributions back to that common pool of software if they choose to
do so.

The same distribution tools can also be used to distribute software
within an organisation, regardless of whether that software is
published as open source software or not.


Installing the tools
====================

The standard library does not include build tools that support modern
Python packaging standards, as the core development team has found
that it is important to have standard tools that work consistently,
even on older versions of Python.

The currently recommended build and distribution tools can be
installed by invoking the "pip" module at the command line:

   python -m pip install setuptools wheel twine

Note:

  For POSIX users (including macOS and Linux users), these
  instructions assume the use of a *virtual environment*.For Windows
  users, these instructions assume that the option to adjust the
  system PATH environment variable was selected when installing
  Python.

The Python Packaging User Guide includes more details on the currently
recommended tools.


Reading the Python Packaging User Guide
=======================================

The Python Packaging User Guide covers the various key steps and
elements involved in creating and publishing a project:

* Project structure

* Building and packaging the project

* Uploading the project to the Python Package Index

* The .pypirc file


How do I…?
==========

These are quick answers or links for some common tasks.


… choose a name for my project?
-------------------------------

This isn’t an easy topic, but here are a few tips:

* check the Python Package Index to see if the name is already in use

* check popular hosting sites like GitHub, Bitbucket, etc to see if
  there is already a project with that name

* check what comes up in a web search for the name you’re considering

* avoid particularly common words, especially ones with multiple
  meanings, as they can make it difficult for users to find your
  software when searching for it


… create and distribute binary extensions?
------------------------------------------

This is actually quite a complex topic, with a variety of alternatives
available depending on exactly what you’re aiming to achieve. See the
Python Packaging User Guide for more information and recommendations.

See also: Python Packaging User Guide: Binary Extensions
