[Python-Dev] INPLACE_ADD and INPLACE_MULTIPLY oddities in ceval.c
Travis Oliphant
oliphant.travis at ieee.org
Tue Mar 28 03:08:00 CEST 2006
If you have Numeric or numpy installed try this:
#import Numeric as N
import numpy as N
a = range(10)
b = N.arange(10)
a.__iadd__(b)
print a
Result:
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Contrast the returned output with
import numpy as N
a = range(10)
b = N.arange(10)
a += b
print a
Result:
[ 0 2 4 6 8 10 12 14 16 18]
Having "a+=b" and "a.__iadd__(b)" do different things seems like an
unfortunate bug.
It seems to me that the problem is that the INPLACE_ADD and
INPLACE_MULTIPLY cases in ceval.c use PyNumber_InPlace<YYY> instead of
trying PySequence_InPlace<YYY> when the object doesn't support the
in-place number protocol.
I could submit a patch if there is agreement that this is a problem.
-Travis
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