Hello,
I came accross what i think is a serious bug in the python interpreter.
Membership testing seems not to work for list of objects when these
objects have a user-defined __cmp__ method.
It is present in Python 2.3 and 2.4. I don't know about other versions.
The following code illustrates the bug:
from random import choice
class OBJ:
def __init__(self,identifier):
self.id=identifier
self.allocated=0
def __cmp__(self,other):
return cmp(other.allocated,self.allocated)
mylist=[OBJ(i) for i in range(20)]
excluded=[obj for obj in mylist if obj.id>choice(range(20))]
for obj in mylist:
if obj in excluded:
assert obj.id in [objt.id for objt in excluded]
continue
Running the above snippet will trigger the assert. The culprit seems to
be the __cmp__ method which sorts on a key with constant value.
Best regards
Alain
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