propcache

The module provides a fast implementation of cached properties for Python 3.9+.

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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.:

.. code-block:: console

$ 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 <https://github.com/aio-libs/propcache/issues>_ 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.

.. _GitHub: https://github.com/aio-libs/propcache

=========
Changelog

..
You should NOT be adding new change log entries to this file, this
file is managed by towncrier. You may edit previous change logs to
fix problems like typo corrections or such.
To add a new change log entry, please see
https://pip.pypa.io/en/latest/development/#adding-a-news-entry
we named the news folder "changes".

WARNING: Don't drop the next directive!

.. towncrier release notes start

0.3.2

(2025-06-09)

Improved documentation

Fixed incorrect decorator usage in the ~propcache.api.under_cached_property example code -- by @meanmail <https://github.com/sponsors/meanmail>__.

Related issues and pull requests on GitHub:
#109 <https://github.com/aio-libs/propcache/issues/109>__.

Packaging updates and notes for downstreams

Updated to use Cython 3.1 universally across the build path -- by @lysnikolaou <https://github.com/sponsors/lysnikolaou>__.

Related issues and pull requests on GitHub:
#117 <https://github.com/aio-libs/propcache/issues/117>__.
Made Cython line tracing opt-in via the with-cython-tracing build config setting -- by @bdraco <https://github.com/sponsors/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 <https://github.com/aio-libs/propcache/issues/118>__.

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 <https://github.com/sponsors/Dreamsorcerer>__.

Related issues and pull requests on GitHub:
#103 <https://github.com/aio-libs/propcache/issues/103>__.

0.3.0

(2025-02-20)

Features

Implemented support for the free-threaded build of CPython 3.13 -- by @lysnikolaou <https://github.com/sponsors/lysnikolaou>__.

Related issues and pull requests on GitHub:
#84 <https://github.com/aio-libs/propcache/issues/84>__.

Packaging updates and notes for downstreams

Started building wheels for the free-threaded build of CPython 3.13 -- by @lysnikolaou <https://github.com/sponsors/lysnikolaou>__.

Related issues and pull requests on GitHub:
#84 <https://github.com/aio-libs/propcache/issues/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 <https://github.com/sponsors/webknjaz>__ that takes into account ABI stability and the exact
version of Python runtime.

.. _re-actors/cache-python-deps:
https://github.com/marketplace/actions/cache-python-deps

Related issues and pull requests on GitHub:
#93 <https://github.com/aio-libs/propcache/issues/93>__.

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 <https://github.com/sponsors/ajsanchezsanz>__ and
@markgreene74 <https://github.com/sponsors/markgreene74>__.

Related commits on GitHub:
64df0a6 <https://github.com/aio-libs/propcache/commit/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 <https://github.com/sponsors/bdraco>__.

Related issues and pull requests on GitHub:
#72 <https://github.com/aio-libs/propcache/issues/72>__.

Removals and backward incompatible breaking changes

Removed support for Python 3.8 as it has reached end of life -- by @bdraco <https://github.com/sponsors/bdraco>__.

Related issues and pull requests on GitHub:
#57 <https://github.com/aio-libs/propcache/issues/57>__.

Packaging updates and notes for downstreams

Stopped implicitly allowing the use of Cython pre-release versions when
building the distribution package -- by @ajsanchezsanz <https://github.com/sponsors/ajsanchezsanz>__ and
@markgreene74 <https://github.com/sponsors/markgreene74>__.

Related commits on GitHub:
64df0a6 <https://github.com/aio-libs/propcache/commit/64df0a6>__.

0.2.0

(2024-10-07)

Bug fixes

Fixed loading the C-extensions on Python 3.8 -- by @bdraco <https://github.com/sponsors/bdraco>__.

Related issues and pull requests on GitHub:
#26 <https://github.com/aio-libs/propcache/issues/26>__.

Features

Improved typing for the propcache.api.under_cached_property decorator -- by @bdraco <https://github.com/sponsors/bdraco>__.

Related issues and pull requests on GitHub:
#38 <https://github.com/aio-libs/propcache/issues/38>__.

Improved documentation

Added API documentation for the propcache.api.cached_property and propcache.api.under_cached_property decorators -- by @bdraco <https://github.com/sponsors/bdraco>__.

Related issues and pull requests on GitHub:
#16 <https://github.com/aio-libs/propcache/issues/16>__.

Packaging updates and notes for downstreams

Moved propcache.api.under_cached_property and propcache.api.cached_property to propcache.api -- by @bdraco <https://github.com/sponsors/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 <https://github.com/aio-libs/propcache/issues/19>, #24 <https://github.com/aio-libs/propcache/issues/24>, #32 <https://github.com/aio-libs/propcache/issues/32>__.
Converted project to use a src layout -- by @bdraco <https://github.com/sponsors/bdraco>__.

Related issues and pull requests on GitHub:
#22 <https://github.com/aio-libs/propcache/issues/22>, #29 <https://github.com/aio-libs/propcache/issues/29>, #37 <https://github.com/aio-libs/propcache/issues/37>__.

0.1.0

(2024-10-03)

Features

Added armv7l wheels -- by @bdraco <https://github.com/sponsors/bdraco>__.

Related issues and pull requests on GitHub:
#5 <https://github.com/aio-libs/propcache/issues/5>__.

0.0.0

(2024-10-02)

Initial release.

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