On Mon, Jun 2, 2008 at 9:28 PM, Brandon Mintern <bmintern@gmail.com> wrote:
I thought max was implemented using += (i.e. it usually starts at 0 and uses += on each item in the iterable). If so, implementing ** _iadd_ ** would result in exactly the code you posted. I realize that I said __add__ in the first place, but __iadd__ is really what I meant.
No, it uses __add__: $ python -c " class Set(set): __iadd__=set.__ior__ sum([Set([1]), Set([2])], Set()) " Traceback (most recent call last): File "<string>", line 3, in <module> TypeError: unsupported operand type(s) for +: 'Set' and 'Set' You can easily see the quadratic behavior of __add__: $ python -m timeit -s "class Set(set): __add__=set.__or__" "sum( (Set(range(i*10, i*10+10)) for i in xrange(100)), Set())" 100 loops, best of 3: 2.4 msec per loop $ python -m timeit -s "class Set(set): __add__=set.__or__" "sum( (Set(range(i*10, i*10+10)) for i in xrange(200)), Set())" 100 loops, best of 3: 8.04 msec per loop $ python -m timeit -s "class Set(set): __add__=set.__or__" "sum( (Set(range(i*10, i*10+10)) for i in xrange(400)), Set())" 10 loops, best of 3: 33.3 msec per loop $ python -m timeit -s "class Set(set): __add__=set.__or__" "sum( (Set(range(i*10, i*10+10)) for i in xrange(800)), Set())" 10 loops, best of 3: 141 msec per loop $ python -m timeit -s "class Set(set): __add__=set.__or__" "sum( (Set(range(i*10, i*10+10)) for i in xrange(1600)), Set())" 10 loops, best of 3: 684 msec per loop George