> Johan's suggestion is very intriguing but, unless I am completely mistaken, > it does not work in python. If I understand correctly if O is an instance of > Foo and O does not have the attribute x then python looks for Foo().x
You're right, I seem to have confused myself with deleting attributes of subclasses. Another possibility is to create micro-classes for each method which only certain matrices have, and then dynamically monkey-patch each constructed matrix to inherit from the micro-classes it should. Unfortunately this requires assigning to o.__class__, which doesn't seem possible when o is an instance of a Cython class. Otherwise, the code below could work, I believe. The `extend_instance` is taken from http://stackoverflow.com/questions/8544983/dynamically-mixin-a-base-class-to-an-instance-in-python. def extend_instance(obj, cls): """Apply mixins to a class instance after creation""" base_cls = obj.__class__ base_cls_name = obj.__class__.__name__ obj.__class__ = type(base_cls_name, (base_cls, cls),{}) class IntegerMatrixTwoColumn(SageObject): def magic_method(self): return 42 def MyMatrix(*args): M = matrix(*args) if M.ncols() == 2 and M.base_ring() == ZZ: extend_instance(M, IntegerMatrixTwoColumn) sage: M = MyMatrix(ZZ, 2, 2, [1,2,3,4]) sage: M.magic_method() 42 Best, Johan -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
