Hi Riikka,
> On Aug 31, 2020, at 14:13, Riikka Kalliomäki <riikka.kalliom...@riimu.net>
> wrote:
>
> A common pattern that I've seen that could dearly use PHP internal
> optimization, if possible, would be:
>
> foreach (array_keys($array) as $key) {
> }
I have a draft RFC (https://wiki.php.net/rfc/foreach_void) and patch
(https://github.com/jbafford/php-src/tree/foreachvoid against php 7.0, I think)
that helps with this, by allowing the following syntax:
foreach($iterable as $key => void) { ... }
This would iterate over the keys of the iterable, and does not retrieve the
values at all.
In theory, this should be a general performance win any time one needs to
iterate over only the keys of an iterable, because it does not require the use
of an O(n) iteration and building of the array that array_keys() would, plus it
works on non-array types (such as generators or iterators). It also is more
performant than foreach($iterable as $key => $_) {}, because it omits the
opcode that instructs the engine to retrieve the value. (Presumably, a future
direction could include using this request to inform generators or iterators to
only return keys, and not values, which could further improve performance,
especially if value generation is expensive. But that is out of scope for this
RFC.)
If this is something we'd like for PHP 8.1 and there are no major objections to
the idea, then after 8.0 is released, I can move the RFC out of Draft and into
Under Discussion, and presuming a vote passes, I'll update the patch as
necessary to work against 8.0. But my time is limited and I'm not willing to
put further time into the code unless an RFC vote passes.
Thoughts anyone?
-John
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