From: Aleksei Guzev <aleksei.guzev@...>
Date: 2002-11-19T13:28:31+09:00
Subject: Re: ruby-dev summary 18711-18810


"Bob Alexander" <bobalex@attbi.com> wrote in message
news:007701c28f24$64c657b0$1c72ea0c@C322162A...
> On "zip":
>
> I'm sure most readers of this thread are aware that the snake-language
> introduced about two years ago a "zip" function very much like the method
> being proposed here -- same name and everything. Although I'm a Ruby fan
and
> write lots of Ruby, I do a lot of programming in Python since my company's
> product has lots of Python code. And I can't actually remember ever using
> "zip". Parallel iteration is an occasional need (in my world), but not
> exactly a *frequent* need. When parallel iteration is needed, other
> techniques like each_with_index work just fine. This is a YAGNI (the
acronym
> I just learned :-) warning.
>
> One of the reasons I don't like using Python's "zip" is that it actually
> zips up all of the input sequences into a physical result sequence
(similar
> to their "range" function which is semantically like Ruby's "m...n" but
> returns a physical sequence) -- it's always bothered me to have to create
a
> possibly large sequence to do that operation when it isn't necessary.
> Hopefully, if "zip" becomes part of Ruby, the implementation could be as
an
> iterator which never builds a physical version of the zipped sequence. But
> that is an implementation challenge if the input sequence are general
> instances of Enumerable, since the input sequences cannot be efficiently
> iterated in parallel. (If the input Enumerables were limited to those
which
> are numerically indexed, such as Arrays, implementation would be easy --
but
> it would be unfortunate to have to make that restriction.)
>
> Anyway, my personal feeling about "zip" is that I would likely use it only
> if it could efficiently iterate the zipped elements of the input sequences
> without creating a full physical output sequence. Otherwise, I don't think
> it's especially useful.
>
> By the way, I just scanned the Python library code in the most recent
> distribution and, outside of test modules, there are only two occurrences
of
> "zip"!
>
>
> Bob
>
>

That's right. Again the debates show versatile Ruby's "abilities". It allows
implementing "zipping operation" just as one needs. Writing the code one
will have full control of what the method does.