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 <devguide>` by the same community that maintains Python. We welcome your contributions to Python!

Quick reference

Here are the basic steps needed to get set up and contribute a pull request. This is meant as a checklist, once you know the basics. For complete instructions please see the :ref:`setup guide <setup>`.

Install and set up :ref:`Git <vcsetup>` and other dependencies (see the :ref:`Git Setup <setup>` page for detailed information).
Fork the CPython repository to your GitHub account and :ref:`get the source code <checkout>` using:
```
git clone https://github.com/<your_username>/cpython
cd cpython
```

Build Python:

.. tab:: Unix

   .. code-block:: shell

      ./configure --with-pydebug && make -j $(nproc)

.. tab:: macOS

   .. code-block:: shell

      ./configure --with-pydebug && make -j8

.. tab:: Windows

   .. code-block:: dosbatch

      PCbuild\build.bat -e -d

:ref:`Run the tests <runtests>`:

.. tab:: Unix

   .. code-block:: shell

      ./python -m test -j3

.. tab:: macOS

   .. code-block:: shell

      ./python.exe -m test -j8

   Note: :ref:`Most <mac-python.exe>` macOS systems use
   :file:`./python.exe` in order to avoid filename conflicts with
   the ``Python`` directory.

.. tab:: Windows

   .. code-block:: dosbatch

      .\python.bat -m test -j3

Create a new branch where your work for the issue will go, for example:
```
git checkout -b fix-issue-12345 main
```
If an issue does not already exist, please create it. Trivial issues (for example, typo fixes) do not require any issue to be created.

Once you fixed the issue, run the tests, and the patchcheck:

.. tab:: Unix

   .. code-block:: shell

      make patchcheck

.. tab:: macOS

   .. code-block:: shell

      make patchcheck

.. tab:: Windows

   .. code-block:: dosbatch

      .\python.bat Tools\patchcheck\patchcheck.py

If everything is ok, commit.

Push the branch on your fork on GitHub and :ref:`create a pull request <pullrequest>`. Include the issue number using gh-NNNN in the pull request description. For example:
```
gh-12345: Fix some bug in spam module
```
Add a News entry into the Misc/NEWS.d directory as individual file. The news entry can be created by using blurb-it, or the :pypi:`blurb` tool and its blurb add command. Please read more about blurb in its repository.

Note

First time contributors will need to sign the Contributor Licensing Agreement (CLA) as described in the :ref:`Licensing <cla>` section of this guide.

Quick links

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

Issue tracker
Buildbot status
:ref:`help`
PEPs (Python Enhancement Proposals)
:ref:`gitbootcamp`

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 Core Python Mentorship group is available to help guide new contributors through the process.

A number of individuals from the Python community have contributed to a series of excellent guides at Open Source Guides.

Core developers and contributors alike will find the following guides useful:

How to Contribute to Open Source
Building Welcoming Communities

Guide for contributing to Python:

Contributors	Documentarians	Triagers	Core Developers
:ref:`setup`	:ref:`docquality`	:ref:`tracker`	:ref:`responsibilities`
:ref:`help`	:ref:`documenting`	:ref:`triaging`	:ref:`developers`
:ref:`pullrequest`	:ref:`style-guide`	:ref:`helptriage`	:ref:`committing`
:ref:`runtests`	:ref:`rst-primer`	:ref:`experts`	:ref:`devcycle`
:ref:`fixingissues`	:ref:`translating`	:ref:`labels`	:ref:`motivations`
:ref:`communication`	:ref:`devguide`	:ref:`gh-faq`	:ref:`experts`
:ref:`gitbootcamp`		:ref:`triage-team`
:ref:`devcycle`

We recommend that the documents in this guide be read as needed. 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:

:ref:`stdlibchanges`
:ref:`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 examples 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
MicroPython: A tiny Python interpreter with small subset of the Python standard library that is optimised to run on microcontrollers and in constrained environments.
CircuitPython: A fork of MicroPython designed to simplify experimenting and learning to code on low-cost microcontroller boards.

Key resources

Coding style guides
- PEP 7 (Style Guide for C Code)
- PEP 8 (Style Guide for Python Code)
Issue tracker
- :ref:`experts`
Buildbot status
Source code
- Browse online
- Snapshot of the *main* branch
PEPs (Python Enhancement Proposals)
:ref:`help`
:ref:`developers`

Additional resources

Anyone can clone the sources for this guide. See :ref:`devguide`.
Help with ...
Tool support
- :ref:`gdb`
- :ref:`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 (for example, 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.

Status of Python branches

Moved to :ref:`versions`

Full table of contents

.. toctree::
   :maxdepth: 3

   getting-started/index
   developer-workflow/index
   triage/index
   documentation/index
   testing/index
   development-tools/index
   core-developers/index
   internals/index
   versions
   contrib/index

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