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Date: Fri, 17 Mar 2017 04:02:31 -0300
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To: Niklas Keller <me@kelunik.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Let range() return a generator?
From: david.proweb@gmail.com (David Rodrigues)

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I guess that a lot of PHP functions that could be replaced by a Generator
(basically all array functions like array_values(), array_keys(), etc).
But there are a big question: could it be applied to any case? It will be
faster than just an array? Certainly it will be more memory optimized.

About BC, it really could happen. Currently you could use range() that will
returns an array, then if you use functions like is_array() it will fail to
range() with that change.
One option is mark a Generator acceptable for is_array(), but it generates
another BC, and not make much sense.

The best option is mark it as PHP 8.x BC, simplifying all returned arrays
to a Generator (if it really help on performance).

2017-03-17 3:40 GMT-03:00 Niklas Keller <me@kelunik.com>:

> >
> > For me,
> >
> >     foreach (range($low, $high) as $i)
> >
> > is easier to understand than
> >
> >     for ($i = 0; $i <= $high; $i++)
> >
> > By easier to understand I do not only mean that the beginning of the loop
> > marked by the foreach/range construct is easier to read. While reading
> the
> > body of the loop I can be sure that $i is not unexpectedly modified, for
> > instance.
> >
> > Be that as it may, what I would like to propose should be useful for use
> > cases other than the one (see above) that triggered me thinking about
> this.
> >
> > range() returns an array that contains all elements requested. Depending
> > on the amount of elements, this might not be optimal.
> >
> > One of the most common usages of generators that I have seen is an
> > alternative, userland implementation of the range() function:
> >
> >     function xrange($start, $end, $step = 1) {
> >         for ($i = $start; $i <= $end; $i += $step) {
> >             yield $i;
> >         }
> >     }
> >
> > This makes me wonder: would there be a benefit in changing the
> > implementation of range() to return a generator instead of an array? And
> if
> > so, would this constitute a break in backward compatibility?
>
>
> Yes, that's a BC break. Instead of changing it, there could be a new
> function. But as it can be simply built in userland, I don't see much
> reason to have it in core.
>
> Regards, Niklas
>



-- 
David Rodrigues

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