Python Developer's Guide

This guide is a comprehensive resource for :ref:`contributing <contributing>` to Python -- for both new and experienced contributors. It is :ref:`maintained <helping-with-the-developers-guide>` by the same community that maintains Python. We welcome your contributions to Python!

Quick Start

Here are the basic steps needed to get :ref:`set up <setup>` and contribute a patch:

Install and set up :ref:`Git <vcsetup>` and other dependencies (see the :ref:`Get Setup <setup>` page for detailed information).
Fork the CPython repository on GitHub and :ref:`get the source code <checkout>` using:
```
git clone https://github.com/<your_username>/cpython
```
Build Python, on UNIX and Mac OS use:
```
./configure --with-pydebug && make -j
```
and on Windows use:
```
PCbuild\build.bat -e -d
```
See also :ref:`more detailed instructions <compiling>`, :ref:`how to build dependencies <build-dependencies>`, and the plaform-specific pages for :ref:`UNIX <unix-compiling>`, :ref:`Mac OS <MacOS>`, and :ref:`Windows <windows-compiling>`.
:doc:`Run the tests <runtests>`:
```
./python -m test -j3
```
On :ref:`most <mac-python.exe>` Mac OS X systems, replace :file:`./python` with :file:`./python.exe`. On Windows, use :file:`python.bat`. With Python 2.7, replace test with test.regrtest.
Create a new branch where to work on an issue with:
```
git checkout -b new_branch_name master
```
If an issue does not already exist, please create it. Trivial issues (e.g. typo fixes) do not require any issue to be created.
Once you fixed the issue, run the tests, run make patchcheck, and if everything is ok, commit.
Push the branch on your fork and :doc:`create a pull request <pullrequest>`. Include the issue number using bpo-NNNN in the pull request description. For example:
```
bpo-12345: Fix some bug in spam module
```

Quick Links

Here are some links that you probably will reference frequently while contributing to Python:

Issue tracker
Buildbot status
:doc:`help`
PEPs (Python Enhancement Proposals)
:doc:`gitdevs`

Status of Python branches

Branch	Schedule	Status	First release	End-of-life	Comment
default	PEP 537	features	2018-06-15	2023-06-15	The default branch is currently the future version Python 3.7.
3.6	PEP 494	bugfix	2016-12-23	2021-12-23
3.5	PEP 478	bugfix	2015-09-13	2020-09-13
2.7	PEP 373	bugfix	2010-07-03	2020-01-01	The support has been extended to 2020.
3.4	PEP 429	security	2014-03-16	2019-03-16	Last binary release: Python 3.4.4
3.3	PEP 398	security	2012-09-29	2017-09-29	Last binary release: Python 3.3.5
3.2	PEP 392	end-of-life	2011-02-20	2016-02-20	Last binary release: Python 3.2.5
3.1	PEP 375	end-of-life	2009-06-27	2012-04-11	Last release: Python 3.1.5
3.0	PEP 361	end-of-life	2008-12-03	2009-01-13	Last release: Python 3.0.1
2.6	PEP 361	end-of-life	2008-10-01	2013-10-29	Last release: Python 2.6.9

Status:

features:	new features are only added to the default branch, this branch accepts any kind of change.
bugfix:	bugfixes and security fixes are accepted, new binaries are still released.
security:	only security fixes are accepted and no more binaries are released, but new source-only versions can be released
end-of-life:	branch no longer maintained; no more changes can be pushed to this branch.

Dates in italic are scheduled and can be adjusted.

By default, the end-of-life is scheduled 5 years after the first release. It can be adjusted by the release manager of each branch. Versions older than 2.7 have reached end-of-life.

Contributing

We encourage everyone to contribute to Python and that's why we have put up this developer's guide. If you still have questions after reviewing the material in this guide, then the Python Mentors group is available to help guide new contributors through the process.

Guide for contributing to Python:

:doc:`setup`
:doc:`help`
:doc:`pullrequest`
:doc:`runtests`
Beginner tasks to become familiar with the development process
- :doc:`docquality`
- :doc:`coverage`
Advanced tasks for once you are comfortable
- :doc:`silencewarnings`
- Fixing issues found by the :doc:`buildbots <buildbots>`
- :doc:`fixingissues`
:ref:`tracker` and :ref:`helptriage`
- :doc:`triaging`
- :doc:`experts`
:doc:`communication`
:doc:`coredev`
:doc:`gitdevs`

It is recommended that the above documents be read in the order listed. You can stop where you feel comfortable and begin contributing immediately without reading and understanding these documents all at once. If you do choose to skip around within the documentation, be aware that it is written assuming preceding documentation has been read so you may find it necessary to backtrack to fill in missing concepts and terminology.

Proposing changes to Python itself

Improving Python's code, documentation and tests are ongoing tasks that are never going to be "finished", as Python operates as part of an ever-evolving system of technology. An even more challenging ongoing task than these necessary maintenance activities is finding ways to make Python, in the form of the standard library and the language definition, an even better tool in a developer's toolkit.

While these kinds of change are much rarer than those described above, they do happen and that process is also described as part of this guide:

:doc:`stdlibchanges`
:doc:`langchanges`

Other Interpreter Implementations

This guide is specifically for contributing to the Python reference interpreter, also known as CPython (while most of the standard library is written in Python, the interpreter core is written in C and integrates most easily with the C and C++ ecosystems).

There are other Python implementations, each with a different focus. Like CPython, they always have more things they would like to do than they have developers to work on them. Some major example that may be of interest are:

PyPy: A Python interpreter focused on high speed (JIT-compiled) operation on major platforms
Jython: A Python interpreter focused on good integration with the Java Virtual Machine (JVM) environment
IronPython: A Python interpreter focused on good integration with the Common Language Runtime (CLR) provided by .NET and Mono
Stackless: A Python interpreter focused on providing lightweight microthreads while remaining largely compatible with CPython specific extension modules

Key Resources

Coding style guides
- PEP 7 (Style Guide for C Code)
- PEP 8 (Style Guide for Python Code)
Issue tracker
- Meta tracker (issue tracker for the issue tracker)
- :doc:`experts`
- Firefox search engine plug-in
Buildbot status
Source code
PEPs (Python Enhancement Proposals)
:doc:`help`
:doc:`developers`

Additional Resources

Anyone can clone the sources for this guide. See :ref:`helping-with-the-developers-guide`.
Help with ...
- :doc:`grammar`
- :doc:`compiler`
Tool support
- :doc:`gdb`
- :doc:`clang`
- Various tools with configuration files as found in the Misc directory
- Information about editors and their configurations can be found in the wiki
python.org maintenance
:ref:`Search this guide <search>`

Code of Conduct

Please note that all interactions on Python Software Foundation-supported infrastructure is covered by the PSF Code of Conduct, which includes all infrastructure used in the development of Python itself (e.g. mailing lists, issue trackers, GitHub, etc.). In general this means everyone is expected to be open, considerate, and respectful of others no matter what their position is within the project.

Full Table of Contents

.. toctree::
   :numbered:

   setup
   help
   pullrequest
   runtests
   coverage
   docquality
   documenting
   silencewarnings
   fixingissues
   tracker
   triaging
   communication
   porting
   coredev
   developers
   committing
   devcycle
   buildbots
   stdlibchanges
   langchanges
   experts
   gdb
   grammar
   compiler
   coverity
   clang
   buildslave
   gitdevs
   motivations

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