From 8f68cb7db37322cfeeb8338e78474e5f25d930c5 Mon Sep 17 00:00:00 2001 From: Cheryl Sabella Date: Fri, 26 Jan 2018 21:45:24 -0500 Subject: [3.6] bpo-27505: Retrofit module __class__ documentation from 3.7 (GH-5321) The module `__class__` attribute documentation added to 3.7 for PEP 562 (dynamic module attributes) also applies to earlier versions. This backports that subset of the new docs to the 3.6 branch so that it will appear in the main online documentation and in the final 3.6 binary release. Patch by Cheryl Sabella. --- Doc/reference/datamodel.rst | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index cd11020..9752494 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -1500,6 +1500,39 @@ access (use of, assignment to, or deletion of ``x.name``) for class instances. returned. :func:`dir` converts the returned sequence to a list and sorts it. +Customizing module attribute access +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +.. index:: + single: __class__ (module attribute) + +For a more fine grained customization of the module behavior (setting +attributes, properties, etc.), one can set the ``__class__`` attribute of +a module object to a subclass of :class:`types.ModuleType`. For example:: + + import sys + from types import ModuleType + + class VerboseModule(ModuleType): + def __repr__(self): + return f'Verbose {self.__name__}' + + def __setattr__(self, attr, value): + print(f'Setting {attr}...') + setattr(self, attr, value) + + sys.modules[__name__].__class__ = VerboseModule + +.. note:: + Setting module ``__class__`` only affects lookups made using the attribute + access syntax -- directly accessing the module globals (whether by code + within the module, or via a reference to the module's globals dictionary) + is unaffected. + +.. versionchanged:: 3.5 + ``__class__`` module attribute is now writable. + + .. _descriptors: Implementing Descriptors -- cgit v0.12