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In-Reply-To: <95eddd89-9915-14fc-7649-9de0e8dd349d@gmail.com>
Date: Thu, 3 Sep 2020 00:06:32 -0400
Cc: PHP internals <internals@lists.php.net>
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 <95eddd89-9915-14fc-7649-9de0e8dd349d@gmail.com>
To: Stanislav Malyshev <smalyshev@gmail.com>
Subject: Re: [PHP-DEV] Draft RFC: foreach iteration of keys without values
From: mike@newclarity.net (Mike Schinkel)

> On Sep 2, 2020, at 5:54 PM, Stanislav Malyshev <smalyshev@gmail.com> =
wrote:
>=20
> Hi!
>=20
>>> 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 =3D> $_) {}, because it omits the opcode
>>> that instructs the engine to retrieve the value. (Presumably, a
>>> future direction could include using this request to inform
>>> generators or
>=20
> To me, it looks like the case of premature micro-optimization. Unless
> there's a benchmark that proves it achieves speedup in a real-life
> application (not tight-loop synthetic benchmark) I think
> foreach($iterable as $key =3D> $_) {} is completely fine. My opinion =
has
> been and remains, absent new data, that if your code performance =
hinges
> on a couple of simple opcodes being there, maybe you'd better =
implement
> that part in C, but in most real-life applications it is not and any
> performance gain you might get from such syntax is microscopic.

If it adds a micro-optimization, great, but allowing a developer to =
explicitly signal intent is the primary argument for adding void. IMO.

-Mike