ExtensionClass 6.3

Metaclass for subclassable extension types

ExtensionClass

This package provides a metaclass that allows classes implemented in extension modules to be subclassed in Python. Unless you need ExtensionClasses for legacy applications (e.g. Zope), you probably want to use Python’s new-style classes (available since Python 2.2).

ComputedAttribute

This package provides a way to attach attributes to an ExtensionClass or instance that are computed by calling a callable. This works very much like property known from new-style classes, except that a ComputedAttribute can also be attached to an instance and that it honours ExtensionClass semantics (which is useful for retaining Acquisition wrappers, for example).

MethodObject

This package lets you attach additional “methods” to ExtensionClasses. These “methods” are actually implemented by subclassing the MethodObject.Method class and implementing the __call__ method there. Instances of those classes will be bound to the instances they’re attached to and will receive that instance object as a first parameter (after self).

Change log

6.3 (2026-04-30)

• Add support for automatically building and publishing Windows/ARM64 wheels.

• Add support for automatically building and publishing source distributions.

• Fix compilation on free-threaded Python 3.14t: use Py_REFCNT() macro instead of direct ob_refcnt struct access, guard im_self mutation optimization with #ifndef Py_GIL_DISABLED.

• Add CI testing for free-threaded Python 3.14t (Linux).

6.2 (2025-11-16)

• Move all supported package metadata into pyproject.toml.

6.1 (2025-10-29)

• Drop support for Python 3.8, 3.9.

• Add support for Python 3.14.

6.0 (2024-09-17)

• Build Windows wheels on GHA.

• Add support for Python 3.13.

• Drop support for Python 3.7.

5.1 (2023-10-05)

• Add support for Python 3.12.

5.0 (2023-01-19)

• Drop support for Python 2.7, 3.5, 3.6.

• Fix deprecation warning in tests.

4.9 (2022-11-17)

• Add support for building arm64 wheels on macOS.

4.8 (2022-11-03)

• Update Python 3.11 support to the final release.

4.7 (2022-09-16)

• Update Python 3.11 support to rc2.

• Disable unsafe math optimizations in C code. (#55)

4.6 (2022-01-14)

• Add support for Python 3.10 and 3.11 (as of alpha 3).

4.5.1 (2021-06-11)

• Create wheels for Linux (2010, 2014 and aarch) and MacOS.

4.5.0 (2020-10-07)

• Drop support for Python 3.4.

• Add support for Python 3.8 and 3.9.

• Fix accessing __parent__ when it is defined as a class attribute that is None (e.g., in subclasses of zope.conatiner.contained.Contained). See issue 24.

4.4.0 (2018-10-05)

• Fail if C extensions couldn’t be compiled on compatible platforms.

• Add Appveyor configuration to automate building Windows eggs

• Add support for Python 3.7.

• Fix getting attributes that are data descriptors in the Python implementation.

• Reach and automatically maintain 100% test coverage.

4.3.0 (2017-02-22)

• Drop support for Python 3.3.

• Remove unused C macro from ExtensionClass.h.

• Fix C compilation under Windows.

4.2.1 (2017-02-02)

• Fix problems with computed attribute and property wrapping.

4.2.0 (2017-01-18)

• Port the C extension to Python 3.

• Add support for Python 3.5 and 3.6.

• Drop support for Python 2.6, 3.2.

4.1.2 (2015-04-03)

• Fix calling of __class_init__ hook by Python implementation.

4.1.1 (2015-03-20)

• Avoid wrapping __parent__ in pure-Python version. Matches change made to C version in afb8488. See issue #3.

4.1 (2014-12-18)

• Housekeeping changes only.

4.1b1 (2014-11-12)

• Added compatibility with Python 3.4.

4.1a1 (2013-05-04)

• Added compatibility with Python 3.2 and 3.3 using the Python reference implementation.

• Add Python reference implementation. Used by default on PyPy.

4.0 (2013-02-24)

• Added trove classifiers to project metadata.

4.0a1 (2011-12-13)

• Don’t create wrappers when retrieving parent pointers.

2.13.2 (2010-06-16)

• LP #587760: Handle tp_basicsize correctly.

2.13.1 (2010-04-03)

• Removed undeclared testing dependency on zope.testing.

• Removed cruft in pickle/pickle.c related to removed __getnewargs__.

2.13.0 (2010-02-22)

• Avoid defining __getnewargs__ as not to defeat the ZODB persistent reference optimization. Refs https://bugs.launchpad.net/zope2/+bug/143657. In order to take advantage of this optimization, you need to re-save your objects.

2.12.0 (2010-02-14)

• Removed old build artifacts and some metadata cleanup.

• Added support for method cache in ExtensionClass. Patch contributed by Yoshinori K. Okuji. See https://bugs.launchpad.net/zope2/+bug/486182.

2.11.3 (2009-08-02)

• Further 64-bit fixes (Python 2.4 compatibility).

2.11.2 (2009-08-02)

• Fixed 64-bit compatibility issues for Python 2.5.x / 2.6.x. See http://www.python.org/dev/peps/pep-0353/ for details.

2.11.1 (2009-02-19)

• Initial egg release.