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Clarify the distinction between the definition ns and __dict__.

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Eric Snow 2016-06-11 19:42:03 -06:00
parent 97e820b228
commit 4f37f47475
1 changed files with 7 additions and 3 deletions
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pep-0520.txt
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@ -14,15 +14,19 @@ Post-History: 7-Jun-2016
Abstract Abstract
======== ========
When a class is defined using a ``class`` statement, the class body is
executed within a namespace. After the execution completes, that
namespace is copied into new ``dict`` and the original definition
namespace is discarded. The new copy is stored away as the class's
namespace and is exposed as ``__dict__`` through a read-only proxy.
This PEP changes the default class definition namespace to ``OrderedDict``. This PEP changes the default class definition namespace to ``OrderedDict``.
The long-lived class namespace (``__dict__``) will remain a ``dict``.
Furthermore, the order in which the attributes are defined in each class Furthermore, the order in which the attributes are defined in each class
body will now be preserved in the ``__definition_order__`` attribute of body will now be preserved in the ``__definition_order__`` attribute of
the class. This allows introspection of the original definition order, the class. This allows introspection of the original definition order,
e.g. by class decorators. e.g. by class decorators.
Note: just to be clear, this PEP is *not* about changing ``__dict__`` for
classes to ``OrderedDict``.
Motivation Motivation
========== ==========