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Date: Tue, 15 Apr 2025 00:01:18 +0100
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Subject: Re: [PHP-DEV] Closure::getCurrent() for recursion
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From: krinkle@fastmail.com (Krinkle)

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On Mon, 31 Mar 2025, Jorg Sowa wrote:
> I thought about edge cases and what the desired output is with nested closures?
> 
> Example:
> <?
> $a = function (int $numberA) {
>     $b = function (int $numberB) {
>         if($numberB < 10) {
>             return Closure::current(10);
>         }
>         return $numberB;
>     };
>     return $b($numberA) + $numberA;
> };
> 
> var_dump($a(4));

I'd expect it to refer to current/local/nearest function.

If you wanted a way to call $a from inside $b, I'd expect callable syntax to be able to capture these in-place.

Eg:
 
$a = function ($a) {
  $aFn = Closure::current(...);
  $aFn(4) === Closure::current(4);
};

https://www.php.net/manual/en/functions.first_class_callable_syntax.php

This could be use'd to a nested $b function, or otherwise passed/returned to other functions without changing meaning.

That is, I would not expect it to behave like late-static binding where it'll always be for the "current" fn that's invoking it, but rather capture where the callable expression happened.

--
Timo Tijhof,
Wikimedia Foundation.
https://timotijhof.net/



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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Mon, 31 Mar =
2025, Jorg Sowa wrote:</div><blockquote type=3D"cite" id=3D"qt" style=3D=
""><div dir=3D"ltr"><div dir=3D"ltr"><div><div>I thought about edge case=
s and what the desired output is with nested closures?</div><div><br></d=
iv></div><div>Example:</div><div>&lt;?</div><div>$a =3D function (int $n=
umberA) {</div><div>&nbsp; &nbsp; $b =3D function (int $numberB) {</div>=
<div>&nbsp; &nbsp; &nbsp; &nbsp; if($numberB &lt; 10) {</div><div>&nbsp;=
 &nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; return Closure::current(10);</d=
iv><div>&nbsp; &nbsp; &nbsp; &nbsp; }</div><div>&nbsp; &nbsp; &nbsp; &nb=
sp; return $numberB;</div><div>&nbsp; &nbsp; };</div><div>&nbsp; &nbsp; =
return $b($numberA) + $numberA;</div><div>};</div><div><br></div><div>va=
r_dump($a(4));</div></div></div></blockquote><div><br></div><div>I'd exp=
ect it to refer to current/local/nearest function.</div><div><br></div><=
div>If you wanted a way to call $a from inside $b, I'd expect callable s=
yntax to be able to capture these in-place.</div><div><br></div><div>Eg:=
</div><div>&nbsp;</div><div>$a =3D function ($a) {</div><div>&nbsp; $aFn=
 =3D Closure::current(...);</div><div>&nbsp; $aFn(4) =3D=3D=3D&nbsp;Clos=
ure::current(4);<br></div><div>};</div><div><br></div><div><a href=3D"ht=
tps://www.php.net/manual/en/functions.first_class_callable_syntax.php">h=
ttps://www.php.net/manual/en/functions.first_class_callable_syntax.php</=
a><br></div><div><br></div><div>This could be use'd to a nested $b funct=
ion, or otherwise passed/returned to other functions without changing me=
aning.</div><div><br></div><div>That is, I would not expect it to behave=
 like late-static binding where it'll always be for the "current" fn tha=
t's invoking it, but rather capture where the callable expression happen=
ed.</div><div><br></div><div>--</div><div> Timo Tijhof,</div><div>Wikime=
dia Foundation.</div><div><a href=3D"https://timotijhof.net/">https://ti=
motijhof.net/</a><br></div><div><br></div><div><br></div><div><br></div>=
</body></html>
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