Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:112147
MIME-Version: 1.0
References: <CALZWoqU_qQQiQ5O6Pa8Upxo2FYZ2hpMA0dy9=CZndeEFsijgxA@mail.gmail.com>
 <446c9894-191f-e53b-4534-31c4e7b91d7b@gmail.com> <881e2335-5f81-0d79-6a17-06bc20f14223@gmx.net>
 <7e50dba8b8749b9e32c803d7ded20fab84e21dc74ec9a55d8127e961bb036cd8@mahalux.com>
 <CANS-=pf0J3kmybt69a6uhPO8QmCJtBGoHat+x4ngp0AqJpX9+w@mail.gmail.com>
In-Reply-To: <CANS-=pf0J3kmybt69a6uhPO8QmCJtBGoHat+x4ngp0AqJpX9+w@mail.gmail.com>
Date: Thu, 29 Oct 2020 21:50:50 -0500
Message-ID: <CAESVnVoxWWmru-5JrO06d3jDHtO6oCm3PpUQS1L8zm9+v0bMxg@mail.gmail.com>
To: Lynn <kjarli@gmail.com>
Cc: =?UTF-8?B?TWljaGFlbCBWb8WZw63FoWVrIC0gxIxWVVQgRkVM?= <vorismi3@fel.cvut.cz>, 
	Andreas Leathley <a.leathley@gmx.net>, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000879e3205b2da77cd"
Subject: Re: [PHP-DEV] RFC: Support for multi-line arrow functions
From: pollita@php.net (Sara Golemon)

--000000000000879e3205b2da77cd
Content-Type: text/plain; charset="UTF-8"

On Mon, Oct 5, 2020 at 5:09 AM Lynn <kjarli@gmail.com> wrote:
> How should php deal with the scenario where you want to `use` everything
> and have one variable by reference?
>
> ```
> function () use (*, &$butNotThisOne) {};
> ```

I would take a page out of C++'s book here.  In C++ a closure is (some of
these bits can be omitted for brevity, but I'm not going to describe those
here as it's orthogonal to the topic):

[capture, vars](type argName) -> returnType {
  statements;
  return retVal;
}

Looking specifically at the capture vars section (in the example we are
capturing two variables, one named 'capture', one named 'vars'), there are
wildcards available as well:

[=](bool bval) -> void {}

The equal sign (as above) captures all variables used in the closure by
value.
Similarly, the ampersand `[&](int ival) -> void {}` captures all variables
used by reference.

Exceptions can be added to that list just as you suggested, so:

[=,&foo](double dval) -> double { return foo + dval; }

Or

[&,foo]() -> void { doSomething(foo); }

I think we could apply the same in PHP terms:

function(float $dval) use ($, &$foo) { return $foo + $dval; };
function() use (&$, $foo) { doSomething($foo); };

Plus or minor for parser convenience.

-Sara

--000000000000879e3205b2da77cd--