Let range() return a generator?

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

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.

Whether or not it's in core, the two-pronged approach is what Python does
(range and xrange). Sometimes you want an array and not a generator. That
language is really sympathetic to generator use, but it never forces you to
use them. The core libraries are structured thoughtfully in that regard.

Thanks,
Adam

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.

100% agreed. This is a 3 line function and doing it in userland means
you can use it in 5.5 or later.

function range($low, $high) {
for ($i = $low; $i <= $high; ++$i) { yield $i; }
}

-Sara