propcache 0.5.2

Accelerated property cache

propcache

The module provides a fast implementation of cached properties for Python 3.10+.

Introduction

The API is designed to be nearly identical to the built-in functools.cached_property class, except for the additional under_cached_property class which uses self._cache instead of self.__dict__ to store the cached values and prevents __set__ from being called.

For full documentation please read https://propcache.readthedocs.io.

Installation

$ pip install propcache

The library is Python 3 only!

PyPI contains binary wheels for Linux, Windows and MacOS. If you want to install propcache on another operating system where wheels are not provided, the the tarball will be used to compile the library from the source code. It requires a C compiler and and Python headers installed.

To skip the compilation you must explicitly opt-in by using a PEP 517 configuration setting pure-python, or setting the PROPCACHE_NO_EXTENSIONS environment variable to a non-empty value, e.g.:

$ pip install propcache --config-settings=pure-python=false

Please note that the pure-Python (uncompiled) version is much slower. However, PyPy always uses a pure-Python implementation, and, as such, it is unaffected by this variable.

API documentation

The documentation is located at https://propcache.readthedocs.io.

Source code

The project is hosted on GitHub

Please file an issue on the bug tracker if you have found a bug or have some suggestion in order to improve the library.

Discussion list

aio-libs google group: https://groups.google.com/forum/#!forum/aio-libs

Feel free to post your questions and ideas here.

Authors and License

The propcache package is derived from yarl which is written by Andrew Svetlov.

It’s Apache 2 licensed and freely available.

Changelog

0.5.2

(2026-05-08)

No significant changes.

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0.5.1

(2026-05-08)

No significant changes.

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0.5.0

(2026-05-08)

Features

• Added support for newer type hints and remove Optional and Union from all annotations – by @Vizonex

  Related issues and pull requests on GitHub: #193.

Removals and backward incompatible breaking changes

• Dropped support for Python 3.9 as it has reached end of life.

  Related issues and pull requests on GitHub: #216.

Packaging updates and notes for downstreams

• Changed the Cython build dependency from ~= 3.1.0 to >= 3.2.0, removing the upper version bound to avoid conflicts for downstream packagers – by @jameshilliard and @gundalow.

  The upstream Cython version is pinned to 3.2.4 in the CI/CD environment.

  Related issues and pull requests on GitHub: #184, #188, #214.

• Start building and shipping riscv64 wheels – by @justeph.

  Related issues and pull requests on GitHub: #194.

• The PEP 517 build backend now supports a new build-inplace config setting (and PROPCACHE_BUILD_INPLACE environment variable) for controlling whether to build the project in-tree or in a temporary directory. It only affects wheels and is set up to build in a temporary directory by default. It does not affect editable wheel builds; they will keep being built in-tree regardless.

  Here’s an example of using this setting:

  $ python -m build --config-setting=build-inplace=true

  Additionally, when building wheels in an automatically created temporary directory, the build backend now normalizes the respective file system path to a deterministic source checkout directory by injecting the -ffile-prefix-map compiler option into the CFLAGS environment variable, as suggested by known reproducible build practices.

  The effect is that downstreams will get reproducible build results.

  Related issues and pull requests on GitHub: #218.

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0.4.1

(2025-10-08)

Bug fixes

• Fixed reference leak caused by Py_INCREF because Cython has its own reference counter systems – by @Vizonex.

  Related issues and pull requests on GitHub: #162.

Contributor-facing changes

• Fixes the default value for the os parameter in reusable-build-wheel.yml to be ubuntu-latest instead of ubuntu.

  Related issues and pull requests on GitHub: #155.

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0.4.0

(2025-10-04)

Features

• Optimized propcache by replacing sentinel object for checking if the object is NULL and changed dict API for Python C-API – by @Vizonex.

  Related issues and pull requests on GitHub: #121.

Contributor-facing changes

• Builds have been added for arm64 Windows wheels and the reusable-build-wheel.yml workflow has been modified to allow for an OS value (windows-11-arm) which does not include the -latest postfix – by @finnagin.

  Related issues and pull requests on GitHub: #133.

• Added CI for CPython 3.14 – by @kumaraditya303.

  Related issues and pull requests on GitHub: #140.

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0.3.2

(2025-06-09)

Improved documentation

• Fixed incorrect decorator usage in the ~propcache.api.under_cached_property example code – by @meanmail.

  Related issues and pull requests on GitHub: #109.

Packaging updates and notes for downstreams

• Updated to use Cython 3.1 universally across the build path – by @lysnikolaou.

  Related issues and pull requests on GitHub: #117.

• Made Cython line tracing opt-in via the with-cython-tracing build config setting – by @bdraco.

  Previously, line tracing was enabled by default in pyproject.toml, which caused build issues for some users and made wheels nearly twice as slow.

  Now line tracing is only enabled when explicitly requested via pip install . --config-setting=with-cython-tracing=true or by setting the PROPCACHE_CYTHON_TRACING environment variable.

  Related issues and pull requests on GitHub: #118.

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0.3.1

(2025-03-25)

Bug fixes

• Improved typing annotations, fixing some type errors under correct usage and improving typing robustness generally – by @Dreamsorcerer.

  Related issues and pull requests on GitHub: #103.

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0.3.0

(2025-02-20)

Features

• Implemented support for the free-threaded build of CPython 3.13 – by @lysnikolaou.

  Related issues and pull requests on GitHub: #84.

Packaging updates and notes for downstreams

• Started building wheels for the free-threaded build of CPython 3.13 – by @lysnikolaou.

  Related issues and pull requests on GitHub: #84.

Contributor-facing changes

• GitHub Actions CI/CD is now configured to manage caching pip-ecosystem dependencies using re-actors/cache-python-deps – an action by @webknjaz that takes into account ABI stability and the exact version of Python runtime.

  Related issues and pull requests on GitHub: #93.

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0.2.1

(2024-12-01)

Bug fixes

• Stopped implicitly allowing the use of Cython pre-release versions when building the distribution package – by @ajsanchezsanz and @markgreene74.

  Related commits on GitHub: 64df0a6.

• Fixed wrapped and func not being accessible in the Cython versions of propcache.api.cached_property and propcache.api.under_cached_property decorators – by @bdraco.

  Related issues and pull requests on GitHub: #72.

Removals and backward incompatible breaking changes

• Removed support for Python 3.8 as it has reached end of life – by @bdraco.

  Related issues and pull requests on GitHub: #57.

Packaging updates and notes for downstreams

• Stopped implicitly allowing the use of Cython pre-release versions when building the distribution package – by @ajsanchezsanz and @markgreene74.

  Related commits on GitHub: 64df0a6.

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0.2.0

(2024-10-07)

Bug fixes

• Fixed loading the C-extensions on Python 3.8 – by @bdraco.

  Related issues and pull requests on GitHub: #26.

Features

• Improved typing for the propcache.api.under_cached_property decorator – by @bdraco.

  Related issues and pull requests on GitHub: #38.

Improved documentation

• Added API documentation for the propcache.api.cached_property and propcache.api.under_cached_property decorators – by @bdraco.

  Related issues and pull requests on GitHub: #16.

Packaging updates and notes for downstreams

• Moved propcache.api.under_cached_property and propcache.api.cached_property to propcache.api – by @bdraco.

  Both decorators remain importable from the top-level package, however importing from propcache.api is now the recommended way to use them.

  Related issues and pull requests on GitHub: #19, #24, #32.

• Converted project to use a src layout – by @bdraco.

  Related issues and pull requests on GitHub: #22, #29, #37.

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0.1.0

(2024-10-03)

Features

• Added armv7l wheels – by @bdraco.

  Related issues and pull requests on GitHub: #5.

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0.0.0

(2024-10-02)

• Initial release.