sum for sequences?

[Alf P. Steinbach]

* Steven D'Aprano:
> On Sun, 28 Mar 2010 18:56:26 +0200, Alf P. Steinbach wrote:
> 
>> From a more practical point of view, the sum efficiency could be
>> improved by doing the first addition using '+' and the rest using '+=',
>> without changing the behavior.
> 
> But that would change the behaviour. The __iadd__ method is not the same 
> as the __add__ method, and you can't guarantee that they will behave the 
> same -- or even similarly.

Hm, I don't think it's documented (except if the reference implementation serves 
as documentation) which one is currently used.


> And what about tuples? And subclasses of list/tuples? How many different 
> types need to be optimized?

Point. One would need to check for availability of '+='.


> In practical terms, does anyone actually ever use sum on more than a 
> handful of lists? I don't believe this is more than a hypothetical 
> problem.

Agreed.


Cheers,

- Alf