On Sun, Feb 17, 2013 at 1:36 PM, Eric Snow <ericsnowcurren...@gmail.com> wrote: > (See http://bugs.python.org/issue16251) > > The pickle module looks up special methods on instances rather than > using the behavior described in the language reference (or even just > looking them up on the class). This means that custom > __getattribute__() and __getattr__() implementations may get triggered > (e.g. if there is no __reduce__() implemented). > > Bringing pickle in sync with the language reference would not involve > a big change, but it would impact anyone that relies on the current > behavior. Most notably, proxy types could exist which leverage the > current semantics. > > I look at this as trading one "bug" for another in a . So I want to > get some general feedback on the situation and see what others > consider to be the trade-offs of fixing or not fixing this bug. I'm > particularly interested in existing cases where code uses the current > behavior. With that in hand we could assess what alternatives exist > in those cases or how we could better document workarounds for the > current behavior.
I vaguely recall some discussions about this and other similar cases of metaclass confusion (perhaps related to the copy module). One possible approach is to look specifically for cases where type(obj) != obj.__class__ and handle them differently. The general trend has been towards more consistently ignoring instance attributes when looking up special methods, but you're right that this can be a backwards compatibility minefield. Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
