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To: =?Windows-1252?Q?Tim_D=FCsterhus?= <tim@bastelstu.be>, php internals
	<internals@lists.php.net>, Arnaud Le Blanc <arnaud.lb@gmail.com>
Subject: Re: [PHP-DEV] [RFC] Partial Function Application for instance of
 non-static methods ("$this")
Thread-Topic: [PHP-DEV] [RFC] Partial Function Application for instance of
 non-static methods ("$this")
Thread-Index: AQHci4SOHXoxjkWe4kGGd5AgdWmPO7Ve0Rgn
Date: Thu, 22 Jan 2026 23:25:35 +0000
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From: theodorejb@outlook.com (Theodore Brown)

On Thu, January 22, 2026 at 03:50 Tim D=FCsterhus wrote:=0A=
=0A=
> Arnaud and I would like to start discussion on our RFC =93Partial Functio=
n=0A=
> Application for instance of non-static methods ("$this")=94 which is=0A=
> intended to round-off the Partial Function Application RFC that was=0A=
> accepted recently:=0A=
>=0A=
> https://wiki.php.net/rfc/partial_function_application_this=0A=
=0A=
Hi Tim and Arnaud,=0A=
=0A=
Thank you for your work on this. However, I'm struggling to see the benefit=
=0A=
of this syntax over short closures given the examples in the RFC:=0A=
=0A=
    $dates =3D [=0A=
        new DateTimeImmutable('now'),=0A=
    ];=0A=
=0A=
    $formattedDates =3D array_map(DateTimeImmutable::format($this: ?, "c"),=
 $dates);=0A=
=0A=
This saves only three characters compared to a short closure:=0A=
=0A=
    $formattedDates =3D array_map(fn(DateTimeImmutable $d) =3D> $d->format(=
"c"), $dates);=0A=
=0A=
Furthermore, duplicating the array's type isn't necessary when IDEs and sta=
tic=0A=
analysis can infer it, so short closures can usually be even more concise:=
=0A=
=0A=
    $formattedDates =3D array_map(fn($d) =3D> $d->format("c"), $dates);=0A=
=0A=
=0A=
I also find the use of `$this` as a named argument confusing. It makes it=
=0A=
appear as though the current class instance is somehow being passed to the=
=0A=
method, when this isn't the case.=0A=
=0A=
=0A=
The other example with Symfony Form's `ChoiceType` doesn't sell the syntax=
=0A=
for me, either:=0A=
=0A=
    'choice_label' =3D> Category::getName($this: ?),=0A=
=0A=
A short closure is barely any longer, and makes it easier to add additional=
=0A=
logic when needed:=0A=
=0A=
    'choice_label' =3D> fn(Category $c) =3D> $c->getName(),=0A=
=0A=
    'choice_label' =3D> fn(Category $c) =3D> strtoupper($c->getName()),=0A=
=0A=
=0A=
Ultimately I'm not convinced it's worth it to make the partial function syn=
tax=0A=
and semantics more complicated to support this scenario, given that short=
=0A=
closures already provide similar conciseness and greater flexibility.=0A=
=0A=
Kind regards,  =0A=
Theodore=