Hi,
I was performing some timing tests on a class that inherits from the
built-in list, and got some curious results:
import timeit
class MyList(list):
def __init__(self):
list.__init__(self)
self[:] = [0,0,0]
def __delitem__(self,index):
print 'deleting'
ml = MyList()
def test():
global ml
ml[0] += 0
ml[1] += 0
ml[2] += 0
t = timeit.Timer("test()","from __main__ import test")
print t.timeit()
>> 4.11651382676
import timeit
class MyList(list):
def __init__(self):
list.__init__(self)
self[:] = [0,0,0]
ml = MyList()
def test():
global ml
ml[0] += 0
ml[1] += 0
ml[2] += 0
t = timeit.Timer("test()","from __main__ import test")
print t.timeit()
>> 2.23268591383
Does anybody know why defining __delitem__ is causing the code to run
slower? It is not being called, so I don't see why it would affect
performance. Overriding other sequence operators like __delslice__ does
not exhibit this behavior.
The speed difference doesn't really bother me, but I am curious.
I used Python 2.4 for this test.
-Karl
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