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Date: Wed, 15 Jun 2022 18:59:33 -0500
To: "php internals" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Short Closures 2, aka auto-capture take 3
From: larry@garfieldtech.com ("Larry Garfield")

On Wed, Jun 15, 2022, at 7:05 AM, Guilliam Xavier wrote:
>> > > Because variables are captured by-value, Short Closures can not have
>> > > unintended side effects.
>> >
>> > Those statements are true for scalar values. They are not true for objects:
>>
>> This is shown in the "No unintended side-effects" section of the RFC.
>
> I'm confused by the last example:
>
>     $fn2 = function () use (&$a) { /* code with $a AND $b */ }
>
> Isn't that missing a ", $b" in the `use`?
>
> And like others, I also find that allowing mixing explicit *by-value*
> capture with auto-capture is not really needed and even confusing; if
> you "expect that explicitly capturing by value will be rare in
> practice" you might as well forbid it?

Arnaud and I discussed it, and we're going to drop the mix-autocapture-and-manual functionality.  I was tepid on it to begin with, and it can be confusing.  RFC will be updated soon.

> By the way, what about *arrow* functions? e.g.
>
>     $fn = fn () use (&$ref) => $ref = $val1 + $val2; // assigns and returns
>
> Would that be allowed? Is it really *desirable*?

I don't think it's really desireable.  By-ref closure is unusual, probably even less so in one line closures (though I've not checked that specifically), references are usually a bad idea anyway, and in those unusual cases the long-form is still there if you want to control everything.

--Larry Garfield