On 7 June 2016 at 17:50, Eric Snow <ericsnowcurren...@gmail.com> wrote: > Why is __definition_order__ even necessary? > ------------------------------------------- > > Since the definition order is not preserved in ``__dict__``, it would be > lost once class definition execution completes. Classes *could* > explicitly set the attribute as the last thing in the body. However, > then independent decorators could only make use of classes that had done > so. Instead, ``__definition_order__`` preserves this one bit of info > from the class body so that it is universally available.
The discussion in the PEP 487 thread made me realise that I'd like to see a discussion in PEP 520 regarding whether or not to define __definition_order__ for builtin types initialised via PyType_Ready or created via PyType_FromSpec in addition to defining it for types created via the class statement or types.new_class(). For static types, PyType_Ready could potentially set it based on tp_members, tp_methods & tp_getset (see https://docs.python.org/3/c-api/typeobj.html ) Similarly, PyType_FromSpec could potentially set it based on the contents of Py_tp_members, Py_tp_methods and Py_tp_getset slot definitions Having definition order support in both types.new_class() and builtin types would also make it clear why we can't rely purely on the compiler to provide the necessary ordering information - in both of those cases, the Python compiler isn't directly involved in the type creation process. Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
