[Python-Dev] INPLACE_ADD and INPLACE_MULTIPLY oddities in ceval.c (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Wed Mar 29 02:38:55 CEST 2006

Travis E. Oliphant wrote:

I can't imaging anybody relying on an in-place operations to return a "different" object, but we could make the change and run all the NumPy/SciPy tests to see what happens.

I'm really thinking more about the non-inplace operators. If nb_add and sq_concat are collapsed into a single slot, it seems to me that if you do

a = [1, 2, 3] b = array([4, 5, 6]) c = a + b

then a will be asked "Please add yourself to b", and a will say "Okay, I know how to do that!" and promptly concatenate itself with b.

This would be very different from the current behaviour of Numeric arrays. I don't know whether Numeric users would consider it a serious problem or not, but I think we need to consider the implications before charging ahead too fast with slot unification.

-- Greg

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