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To: "'Dik Takken'" <dik.takken@gmail.com>,
	"'Nikita Popov'" <nikita.ppv@gmail.com>,
	"'Mike Schinkel'" <mike@newclarity.net>
Cc: "'John Bafford'" <jbafford@zort.net>,
	"'PHP internals'" <internals@lists.php.net>
References: <89FF9360-609A-439F-BDBE-B3B4C141E00F@newclarity.net> <CAF+90c8A7oWmM45poXj2goghCa00Jz3fiU7ud-aZgVwCfgXOzQ@mail.gmail.com> <a74ead4b-868e-8d85-9850-72fcdebc3cd9@gmail.com>
In-Reply-To: <a74ead4b-868e-8d85-9850-72fcdebc3cd9@gmail.com>
Date: Thu, 3 Sep 2020 20:14:19 +0800
Message-ID: <006901d681eb$c0cd5c70$42681550$@jhdxr.com>
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Subject: RE: [PHP-DEV] Draft RFC: foreach iteration of keys without values
From: me@jhdxr.com (=?utf-8?b?Q0hVIFpoYW93ZWk=?=)

Regarding the unused variable, I think OPCache should be able to =
identify and eliminate it. I don't think it's necessary to add a new =
syntax here.

Array destructuring sounds like a similar case to me. If you don't like =
[, , $v] =3D$arr, you can use [$_, $_, $v]=3D$arr instead.

Regards,
CHU Zhaowei

-----Original Message-----
From: Dik Takken <dik.takken@gmail.com>=20
Sent: Thursday, September 3, 2020 3:31 AM
To: Nikita Popov <nikita.ppv@gmail.com>; Mike Schinkel =
<mike@newclarity.net>
Cc: John Bafford <jbafford@zort.net>; PHP internals =
<internals@lists.php.net>
Subject: Re: [PHP-DEV] Draft RFC: foreach iteration of keys without =
values

On 02-09-2020 19:13, Nikita Popov wrote:
> Just like the first time this was discussed, I don't think this RFC=20
> makes a sufficient case on why we need explicit syntax for this. Just=20
> ignoring the value is an existing pattern that works across all PHP =
versions:
>=20
>     foreach ($iterable as $key =3D> $_) { ... }

While this works fine, it does introduce an unused variable. Code =
inspection currently complains about that, and for good reason, which is =
annoying.

Even if we decide that it is not worth the trouble for foreach loops, =
there are other cases where this new syntax can work well. Array =
destructuring has already been mentioned.

Another case is the one where a function intentionally does not use one =
of the arguments passed to it. This happens easily when using callbacks =
or when implementing interfaces. A function declaration could look like
this:

  function foo($arg, void) {}

This indicates that the second parameter is intentionally left unused.

Perhaps it is a good idea to generalize the RFC to the general concept =
of "using void to intentionally ignore a variable". Maybe pick just one =
use case for actual implementation and extend later using followup RFCs.

Regards,
Dik Takken

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