ExtensionClass

This package provides a metaclass that allows classes implemented in extension modules (typically written in C) to be subclassed in Python. It's primarily used in legacy Python applications, notably within the Zope and Plone ecosystems, to provide features like a class initializer (`__class_init__`) and the acquisition-oriented `__of__` protocol, which predates some modern Python features. The current version is 6.2 and it is actively maintained by the Zope Foundation.