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From: Ian Kelly <ian.g.kelly@gmail.com>
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Subject: Re: Simple exercise
Date: Mon, 14 Mar 2016 09:16:59 -0600
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On Mon, Mar 14, 2016 at 9:06 AM, Oscar Benjamin
<oscar.j.benjamin@gmail.com> wrote:
> On 14 March 2016 at 14:35, Rick Johnson <rantingrickjohnson@gmail.com> wrote:
>>
>> I would strongly warn anyone against using the zip function
>> unless
> ...
>> I meant to say: absolutely, one hundred percent *SURE*, that
>> both sequences are of the same length, or, absolutely one
>> hundred percent *SURE*, that dropping values is not going to
>> matter. For that reason, i avoid the zip function like the
>> plague. I would much rather get an index error, than let an
>> error pass silently.
>
> I also think it's unfortunate that zip silently discards items. Almost
> always when I use zip I would prefer to see an error when the two
> iterables are not of the same length.

It's sometimes very useful, though. For example on multiple occasions
I've taken advantage of the fact that enumerate(x) is equivalent to
zip(itertools.count(), x). If zip raised an error then that would only
be possible using islice, and then only if the length is known in
advance.

Also, in order for zip to know that the lengths are not equal, it
would have to try to read one additional item from the longer
iterable. That's rather unfortunate if it's an iterator and you're
hoping to catch the exception and then use the rest of the iterator
for something else.