sum() requires number, not simply __add__
Ian Kelly
ian.g.kelly at gmail.com
Thu Feb 23 17:00:07 EST 2012
On Thu, Feb 23, 2012 at 2:53 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Fri, Feb 24, 2012 at 8:41 AM, Arnaud Delobelle <arnodel at gmail.com> wrote:
>> _sentinel = object()
>>>> def sum(iterable, start=_sentinel):
>> if start is _sentinel:
>>>> del _sentinel
>> Somewhat off-topic: Doesn't the if statement there do a lookup for a
> global, which would mean that 'del _sentinel' will cause it to fail?
> Or have I missed something here?
I believe you're correct. If you really want to delete the _sentinel
reference though, you could do:
def sum(iterable, start=object()):
if start is sum.func_defaults[0]:
...
Cheers,
Ian
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