[Python-Dev] listcomps vs. for loops

[Aahz]

On Mon, Oct 20, 2003, Guido van Rossum wrote:
>Aahz:
>>
>> ?!?!  When listcomps were introduced, you were strongly against any
>> changes that would make it difficult to switch back and forth between a
>> listcomp and its corresponding equivalent for loop.
> 
> I don't recall what I said then.  Did I say it was a feature that
> 
>   L = [x for x in R]
>   print x
> 
> would print the last item of R?

What I remember you saying was that it was an unfortunate but necessary
consequence so that it would work the same as

    L = []
    for x in R:
        L.append(x)
    print x

You didn't want to have different semantics for two such similar
constructs ("there's only one way").  You also didn't want to push a
stack frame for listcomps.
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

"It is easier to optimize correct code than to correct optimized code."
--Bill Harlan