Subclassing Numeric arrays.

Jacek Generowicz jacek.generowicz at cern.ch
Tue Oct 14 06:14:54 EDT 2003


The Numeric docs state that "Subclassing Numeric arrays is not
possible due to a limitation of Python."

What is this limitation? My first guess is that it is the unsbclassability
of built-in types, which was addressed by the introduction of
new-style classes ... and, indeed, Numeric.ArrayType.__bases__ lists
object, so it looks like a new style class and therefore it seems to
me that it should be subclassable. Yet, if I try to subclass it, I get
told that it is not an acceptable base type.

Now, there is also a UserArray module in the Numeric distribution,
which, supposedly provides a subclassable analogue of the Numeric
arrays. But attempts to subclass it give an identical error message.

So, what am I missing ?




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