Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:87971
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain hotmail.com designates 65.55.111.97 as permitted sender)
Message-ID: <BLU436-SMTP233358BCED2144A24C749ABE26A0@phx.gbl>
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0 (Mac OS X Mail 8.2 \(2098\))
In-Reply-To: <7BCB36EE-56C8-441F-BF40-954D9FA912A9@lerdorf.com>
Date: Tue, 1 Sep 2015 05:08:57 +0200
CC: Stanislav Malyshev <smalyshev@gmail.com>,
 Nikita Nefedov <inefedor@gmail.com>,
 "internals@lists.php.net" <internals@lists.php.net>
Content-Transfer-Encoding: quoted-printable
References: <BLU436-SMTP13020F8CE8795C628BDC665E26B0@phx.gbl> <55E4C19F.4060704@gmail.com> <op.x384rtfxc9evq2@nikita-pc> <55E4F029.10104@gmail.com> <BLU437-SMTP10528B092289CCAD9B4D8AFE26A0@phx.gbl> <7BCB36EE-56C8-441F-BF40-954D9FA912A9@lerdorf.com>
To: Rasmus Lerdorf <rasmus@lerdorf.com>
Subject: Re: [PHP-DEV] [RFC] [Discussion] Short Closures
From: bobwei9@hotmail.com (Bob Weinand)


> Am 01.09.2015 um 04:55 schrieb Rasmus Lerdorf <rasmus@lerdorf.com>:
>=20
>> On Aug 31, 2015, at 18:04, Bob Weinand <bobwei9@hotmail.com> wrote:
>>=20
>> =46rom the RFC:
>>> all variables used in the body of the anonymous function will =
automatically be bound to the anonymous function closure from the =
defining scope
>>=20
>> The implementation is not capturing all the variables from the outer =
scope, but strictly only these accessed by the variables in the Closure =
itself. Hence that shouldn't be much of an issue.
>=20
> This magic scares me. I made a very deliberate decision In the very =
first implementation of PHP to avoid scope side-effects like this. =
Inside a function everything is local unless explicitly declared not to =
be. This has carried through for the past 20+ years in slightly =
different ways, but the basic rule has stayed consistent even for =
closures. Unless explicitly declared via a use clause, every variable =
inside a closure is local and no cross-scope variable name side-effects =
are possible. I am not convinced that this feature is worth breaking =
that longstanding basic tenet of the language.
>=20
> -Rasmus

I'd like to note that it's binding by value and not by reference nor =
true closing over.
There are no side effects, only importing of the variables.

Also, as stated, an important application is quick closures to be passed =
to e.g. array_map:

/* increment by $y */
$y =3D 10;
$array =3D array_map($x ~> $x + $y, $array);

Here it is very obvious that we want to import a variable. Especially, I =
wonder how
$array =3D array_map(function ($x) use ($y) { return $x + $y; }, =
$array);
is making such simple applications more readable? And especially, what =
value does it add here?

If you want to be scoping-safe, (e.g. in bigger Closures inside a large =
function), there always is the explicit syntax allowing you to do that.
Short Closures are a tool for certain use cases, not a swiss knife.

Bob

P.s.: Just a side-question ... Why did you then think, it's be a great =
idea for include/require to share scope?=