cPyExtPatt 0.3.0

Python C Extension Patterns.

If you need to write C extension for Python then this is the place for you.

The full documentation is on Read the Docs.

Code examples and documentation source are on GitHub. The example and test code is available on PyPi.

Subjects Covered

• Introduction

• A Simple Example

• PyObjects and Reference Counting

• Containers and Reference Counts

• Struct Sequence Objects (a namedtuple in C)

• Exception Raising

• A Pythonic Coding Pattern for C Functions

• Parsing Python Arguments

• Creating New Types

• Setting and Getting Module Globals

• Logging and Frames

• File Paths and Files

• Subclassing and Using super()

• Capsules

• Iterators and Generators

• Context Managers

• Pickling C Extension Types

• Watchers [Python 3.12+]

• Setting Compiler Flags

• Debugging

• Memory Leaks

• Thread Safety

• Source Code Layout

• Using C++ With CPython Code

• Miscellaneous

• Installation

• Further Reading

• TODO

• History

• Index

Project Links

• Source is on GitHub.

• Documentation on Read the Docs.

• Project is on PyPi.

Videos

I have presented some of this, well mostly the chapter “PyObjects and Reference Counting”, at Python conferences so if you prefer videos they are here:

• PyCon UK 2015

• PyCon US 2016

Installation

This is primarily a documentation project hosted on Read the Docs. However all the example code is buildable and testable so if you want to examine that then here is how to get the project.

From PyPi

pip install cPyExtPatt

From Source

Choose a directory of your choice, in this case: ~/dev/tmp.

mkdir -p ~/dev/tmp
cd ~/dev/tmp
git clone https://github.com/paulross/PythonExtensionPatterns.git
cd PythonExtensionPatterns

Virtual Environment

Create a Python environment in the directory of your choice, in this case: ~/dev/tmp/PythonExtensionPatterns/venv_3.11 and activate it:

python3.11 -m venv venv_3.11
source venv_3.11/bin/activate

Install the Dependencies

pip install -r requirements.txt

Running the Tests

You now should be able to run the following commands successfully in ~/dev/tmp/PythonExtensionPatterns with your environment activated:

pytest tests/

Building the Documentation

This will build the html and PDF documentation (requires a latex installation):

cd doc/sphinx
make html latexpdf

History

0.3.0 (2025-03-20)

Added Chapters

• “Containers and Reference Counts” which corrects the Python documentation where that is wrong, misleading or missing.

• “Struct Sequences (namedtuple in C)” which corrects the Python documentation where that is wrong, misleading or missing.

• “Context Managers” with practical C code examples.

• “Watchers” with practical examples for dictionary watchers (Python 3.12+).

• “Installation” for the project.

• “Source Code Layout” for the project.

Changed Chapters

• Update the “Homogeneous Python Containers and C++” chapter.

• Expand the “Memory Leaks” chapter.

• Extended the “Logging” chapter to show how to access the CPython Frame from C.

• Add “Emulating Sequence Types” to the “Creating New Types” chapter.

• Expand the Index.

Other

• Python versions supported: 3.9, 3.10, 3.11, 3.12, 3.13.

• Development Status :: 5 - Production/Stable

• The documentation content, example and test code has roughly doubled since version 0.2.2.

• PDF Documentation is 339 pages.

TODO

• Add “Debugging Python with CLion”.

0.2.2 (2024-10-21)

• Expand note on PyDict_SetItem(), PySet_Add() with code in src/cpy/RefCount/cRefCount.c and tests.

0.2.1 (2024-07-29)

• Python versions supported: 3.9, 3.10, 3.11, 3.12, 3.13 (possibly backwards compatible with Python 3.6, 3.7, 3.8)

• Almost all example code is built and tested against these Python versions.

• Added a chapter on managing file paths and files between Python and C.

• Added a chapter on subclassing from your classes or builtin classes.

• Added a chapter on pickling from C.

• Added a chapter on Capsules.

• Added a chapter on Iterators and Generators.

• Added a chapter on memory leaks and how to detect them.

• Added a chapter on thread safety.

• Update “Homogeneous Python Containers and C++” to refer to https://github.com/paulross/PyCppContainers

• All the documentation has been extensively reviewed and corrected where necessary.

• Development Status :: 5 - Production/Stable

Contributors

Many thanks!

Pull Requests

• https://github.com/marioemmanuel

• https://github.com/miurahr

• https://github.com/gdevanla

• https://github.com/joelwhitehouse

• https://github.com/dhermes

• https://github.com/gst

• https://github.com/adamchainz

• https://github.com/nnathan

Issues

• https://github.com/ngoldbaum

• https://github.com/niki-sp

• https://github.com/ldo

• https://github.com/1a1a11a

• https://github.com/congma

0.1.0 (2014-09-09)

• First release.

• Originally “Examples of reliable coding of Python ‘C’ extensions by Paul Ross.”.

• Development Status :: 3 - Alpha