I found following solution to the problem.
Instead of assigning id directly to __hash__ it has to be wrapped with an
instancemethod object. It is somehow strange that this doesn't happen
automatically and it is also strange that instancemethod isn't exposed in
the type module. However it can easily be done and is speeding things up
by almost an factor of 2.
Thank's again for all the help.
Rüdiger
******************************************************************
class foo(list):
__hash__ = lambda x: id(x)
instancemethod = type(foo.__hash__)
class bar(list):
pass
bar.__hash__ = instancemethod(id, None, bar)
def test0( obj ):
_s_ = set()
_s_add = _s_.add
_s_pop = _s_.pop
for _i_ in xrange(1000000):
_s_add(obj())
_s_pop()
def test1():
return test0(foo)
def test2():
return test0(bar)
if __name__ == '__main__':
test1()
test2()
pass
******************************************************************
python -m cProfile test01.py
6000010 function calls in 30.547 CPU seconds
Ordered by: standard name
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 30.547 30.547 <string>:1(<module>)
1 0.000 0.000 30.547 30.547 test01.py:1(<module>)
1 0.000 0.000 0.000 0.000 test01.py:1(foo)
2 10.784 5.392 30.547 15.273 test01.py:10(test0)
1 0.000 0.000 19.543 19.543 test01.py:18(test1)
1000000 4.554 0.000 6.700 0.000 test01.py:2(<lambda>)
1 0.000 0.000 11.003 11.003 test01.py:20(test2)
1 0.000 0.000 0.000 0.000 test01.py:6(bar)
1 0.001 0.001 30.547 30.547 {execfile}
1000000 2.146 0.000 2.146 0.000 {id}
2000000 8.626 0.000 15.327 0.000 {method 'add' of 'set'objects}
2000000 4.436 0.000 4.436 0.000 {method 'pop' of 'set'objects}
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