New submission from Eric Snow: (related to PEP 422 and issue #17044) The execution namespace from a class definition is passed as the third argument to the metaclass (see builtin___build_class__() in Python/bltinmodule.c). When applicable, which is almost always, the subsequent call to type.__new__() copies that namespace into a new dict which is in turn exposed via the class's __dict__. This matters in the case where a metaclass with __prepare__() gets used (or the PEP 422 equivalent). The language reference[1] should note that the object returned by __prepare__() is copied into a new dict when the class is finally created via the metaclass. [1] http://docs.python.org/3.4/reference/datamodel.html#customizing-class-creati... ---------- assignee: docs@python components: Documentation messages: 184188 nosy: docs@python, eric.snow, ncoghlan priority: normal severity: normal stage: needs patch status: open title: language reference should specify restrictions on class namespace type: enhancement versions: Python 3.4 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue17422> _______________________________________