From: Eric Snow Sent: Tuesday, June 07, 2016 2:52 PM To: Émanuel Barry Cc: Python-Dev Subject: Re: [Python-Dev] PEP: Ordered Class Definition Namespace
"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.
Good point. I'll assume that if we need that we'll do something in the metaclass.
What is the value of type.definition_order()? If you need a mutable copy then pass __definition_order__ to list().
I think I explained it backwards. I meant to have a method on ``type`` (which metaclasses can override at will) which will set what is passed to the resulting __definition_order__ attribute. But it might not be needed, as we can probably sneak that inside the namespace in the metaclass' __new__.
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.
Fair enough.
-eric
-Emanuel