On Tue, Jun 7, 2016 at 11:36 AM, Émanuel Barry <vgr255@live.ca> wrote:
From: Eric Snow * "dunder" attributes (e.g. ``__init__``, ``__module__``) are ignored
What does this imply? If I define some __dunder__ methods, will they simply not be present in __definition_order__? What if I want to keep the order of those? While keeping the order of these might be meaningless in most cases, I don't think there's really a huge problem in doing so. Maybe I'm overthinking it.
"dunder" names (not just methods) will not be present in __definition_order__. I'll add an explanation to the PEP. The gist of it is that they are reserved for use by the interpreter and will always clutter up __definition_order__. Since needing dunder names included in __definition_order__ would be rather exceptional, and there are other options available, leaving them out by default is a matter of practicality.
* ``__definition_order__`` is a tuple * ``__definition_order__`` is a read-only attribute * ``__definition_order__`` is always set:
* if ``__definition_order__`` is defined in the class body then it is used * types that do not have a class definition (e.g. builtins) have their ``__definition_order__`` set to ``None`` * types for which `__prepare__()`` returned something other than ``OrderedDict`` (or a subclass) have their ``__definition_order__`` set to ``None``
I would probably like a ``type.definition_order`` method, for which the return value is bound to __definition_order__ when the class is created (much like the link between ``type.mro`` and ``cls.__mro__``.
What is the value of type.definition_order()? If you need a mutable copy then pass __definition_order__ to list().
Additionally I'm not sure if setting the attribute to None is a good idea; I'd have it as an empty tuple. Then again I tend to overthink a lot.
None indicates that there is no order. An empty tuple indicates that there were no attributes.
__definition_order__ = tuple(k for k in locals() if (!k.startswith('__') or !k.endswith('__')))
Mixing up C and Python syntax here.
nice catch :)
I'm +1 on the whole idea (one of my common uses of metaclasses was to keep the definition order *somewhere*). Thank you for doing that!
:) -eric