I've found the python documentation on this exact behaviour of hash and other special methods by accident (I was looking for something else in the python docs). For a total understanding read 3.4.11 and 3.4.12 of http://docs.python.org/reference/datamodel.html#special-method-lookup-for-old-style-classes .
If you don't want to read it yourself, the reason for the change is that newstyle classes are also objects. sage: class Foo(object): ....: pass ....: sage: isinstance(Foo,object) True So if hash called __hash__ for the instance itself first this would lead to problems if the instance itself was a class whose instances are hashable. -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
