[Python-Dev] Rationale for sum()'s design?

[Greg Ewing]

Guido van Rossum wrote:
> 
> - the identity (defaulting to 0) if the sequence is empty
> - the first and only element if the sequence only has one element
> - (...(((A + B) + C) + D) + ...) if the sequence has more than one element

While this might be reasonable if the identity
argument is not specified, I think that if an
identity is specified, it should be used even
if the sequence is non-empty. The reason being
that the user might be relying on that to get
the semantics he wants.

Think of the second argument as "accumulator
object" rather than "identity".

-- 
Greg Ewing, Computer Science Dept, +--------------------------------------+
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