iSharkFly-Open
/
python-peps
mirror of https://github.com/python/peps.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

clarify more details

This commit is contained in:
Martin Teichmann 2016-07-17 11:47:49 +02:00 committed by GitHub
parent 3d20e37391
commit 1f9366430b
1 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
pep-0487.txt
View File

@ -232,7 +232,7 @@ PEP::
Implementation Details Implementation Details
====================== ======================
The different hooks are called in the following order: ``type.__new__`` calls The hooks are called in the following order: ``type.__new__`` calls
the ``__set_name__`` hooks on the descriptor after the new class has been the ``__set_name__`` hooks on the descriptor after the new class has been
initialized. Then it calls ``__init_subclass__`` on the base class, on initialized. Then it calls ``__init_subclass__`` on the base class, on
``super()``, to be precise. This means that subclass initializers already ``super()``, to be precise. This means that subclass initializers already
@ -245,6 +245,12 @@ even to prevent ``__set_name__`` from being called. Most of the times,
however, such a prevention would be accidental, as it often happens that a call however, such a prevention would be accidental, as it often happens that a call
to ``super()`` is forgotten. to ``super()`` is forgotten.
As a third option, all the work could have been done in ``type.__init__``.
Most metaclasses do their work in ``__new__``, as this is recommended by
the documentation. Many metaclasses modify their arguments before they
pass them over to ``super().__new__``. For compatibility with those kind
of classes, the hooks should be called from ``__new__``.
Another small change should be done: in the current implementation of Another small change should be done: in the current implementation of
CPython, ``type.__init__`` explicitly forbids the use of keyword arguments, CPython, ``type.__init__`` explicitly forbids the use of keyword arguments,
while ``type.__new__`` allows for its attributes to be shipped as keyword while ``type.__new__`` allows for its attributes to be shipped as keyword