On Tue, 09 Dec 2014 00:03:33 -0500, Terry Reedy wrote:
> On 12/8/2014 9:50 PM, Steven D'Aprano wrote:
>> Roy Smith wrote:
>>
>>> Chris Angelico wrote:
>
>>>> def myzip(*args):
>>>> iters = map(iter, args)
>>>> while iters:
>>>> res = [next(i) for i in iters]
>>>> yield tuple(res)
>>>
>>> Ugh. When I see "while foo", my brain says, "OK, you're about to see
>>> a loop which is controlled by the value of foo being changed inside
>>> the loop".
>>
>> Yes. Me too. 99% of the time when you see "while foo", that's what
>> you'll get, so it's the safe assumption. But it's only an assumption,
>> not a requirement. When you read a bit more of the code and see that
>> iters isn't being modified, your reaction ought to be closer "oh wow,
>> that's neat"
>
> To me it is a code smell. iters is empty if and only if args is empty.
> If args is empty, iters should not be created.
>
> if args:
> iters = ...
> while True
> ... (return on exception)
>
> makes the logic clear.
When you understand why this body of code is inelegant and ugly, you
should understand why the above is inelegant and ugly:
def double(x):
if x != 0:
x *= 2
return x
--
Steven
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