In PyQt, wrapped types implement lazy access to the type dictionary through tp_getattro. If the normal attribute lookup fails, then private tables are searched and the attribute (if found) is created on the fly and returned. It is also put into the type dictionary so that it is found next time through the normal lookup. This is done to speed up the import of, and the memory consumed by, the qt module which contains thousands of class methods.
This all works fine - except when super is used. The implementation of super_getattro() doesn't use the normal attribute lookup (ie. doesn't go via tp_getattro). Instead it walks the MRO hierarchy itself and searches instance dictionaries explicitly. This means that attributes that have not yet been referenced (ie. not yet been cached in the type dictionary) will not be found. Questions... 1. What is the reason why it doesn't go via tp_getattro? Bug or feature? 2. A possible workaround is to subvert the ma_lookup function of the type dictionary after creating the type to do something similar to what my tp_getattro function is doing. Are there any inherent problems with that? 3. Why, when creating a new type and eventually calling type_new() is a copy of the dictionary passed in made? Why not take a reference to it? This would allow a dict sub-class to be used as the type dictionary. I could then implement a lazy-dict sub-class with the behaviour I need. 4. Am I missing a more correct/obvious technique? (There is no need to support classic classes.) Many thanks, Phil _______________________________________________ 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
