I had to think a bit to come up with a way to achieve this :) If you subclass Loop and add an "excepthook" property whose fget raises an AttributeError, then PyObject_GetAttrString() will return NULL. Another way is to add a __getattribute__() to the subclass, and raise an AttributeError when the name is "excepthook". Granted, those are corner cases, but they aren't difficult to handle, so I might as well do it properly.