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Date: Fri, 21 Nov 2025 18:10:45 +0000
To: php internals <internals@lists.php.net>
Subject: Re: [PHP-DEV] First-class constructor callables
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")

On 20 November 2025 13:19:09 GMT, Valentin Udaltsov <udaltsov=2Evalentin@gm=
ail=2Ecom> wrote:
>
>I'd like to explore the possibility of adding a first-class callable synt=
ax
>for object constructors:
>
>```
>$factory =3D new Foo(=2E=2E=2E);
>```
>
>The idea is that this expression would produce a Closure which, when
>invoked, calls the constructor with the provided arguments:
>
>```
>$factory =3D new Foo(=2E=2E=2E);
>$object =3D $factory($arg1, $arg2);
>```


Something worth clarifying here is that what you want is not just to *call=
 the constructor*, but to *create the object*=2E In some languages, that's =
the same thing - there's a base object constructor which has to be called -=
 but in PHP, the constructor itself is just a callback hook, called *after*=
 the object exists=2E

And that's where the complexity comes in: "new Foo" isn't a function call,=
 it's an interpreter operation=2E

Here is Nikita's explanation of the issue in the First Class Callable RFC =
<https://wiki=2Ephp=2Enet/rfc/first_class_callable_syntax>

[Begin Quote]

The new Foo() syntax is not considered a call, and as such also not suppor=
ted by the new Foo(=2E=2E=2E) syntax=2E It should be noted that there is al=
so no way to express object creation with traditional callable syntax, and =
it is thus also not supported by Closure::fromCallable()=2E

The general expectation is that new Foo(=2E=2E=2E) would be creating a new=
 instance of Foo on each call, rather than creating a single instance of Fo=
o and then repeatedly calling the constructor=2E To support this, it would =
effectively be necessary to generate a trampoline function of the form

fn(=2E=2E=2E$args) =3D> new Foo(=2E=2E=2E$args)

and acquire a callable to that trampoline instead=2E While certainly possi=
ble, this takes a step backwards from the straightforward semantics of the =
foo(=2E=2E=2E) syntax for ordinary calls=2E

[End Quote]


Rowan Tommins
[IMSoP]