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Date: Tue, 03 Jun 2025 12:03:46 -0500
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Subject: Re: [PHP-DEV] Allow hooks in `readonly` promoted properties
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From: larry@garfieldtech.com ("Larry Garfield")

On Mon, Jun 2, 2025, at 11:34 PM, Nick wrote:

> I would like to add, personally, I don=E2=80=99t believe the above is =
dumb:
>
> ```php
> class Dumb {
> public readonly int $value { get =3D> $this->value * random_int(1, 100=
); }
> }
> ```
>
> I think it is a legitimate use-case.
> Why wouldn=E2=80=99t a `readonly` property allow us to format, cast or=
 however=20
> mutate a =E2=80=9Conly once written value=E2=80=9D on consumption? It =
will not change=20
> the underlying value.
> If it makes things easier for us, allow it. It=E2=80=99s not like this=
 is some=20
> hidden implicit behaviour. We consciously must add the extra code,=20
> hence expect the output to be changed accordingly.

It's about expectation setting.  If you see a property marked `readonly`=
, it's reasonable to expect this to be true:

$foo->bar =3D=3D $foo->bar;

For a traditional field (pre-hooks), this would be trivially true.  With=
 hooks, it may or may not be.  Saying "well, that assumption doesn't hol=
d anymore, deal" is certainly an option, but it's not an option we wante=
d to pursue as part of the larger RFC.  But that is certainly a directio=
n we could take.

> So, I would love to see this RFC to be implemented.
> Maybe you want to move it to discussion? Then my separate thread here=20
> would be obsolete.

I believe at the moment that RFC text is all there is. :-)  I don't know=
 that it's worth opening a discussion without at least a mostly-done imp=
lementation.  Also, Ilija is rather busy on other tasks at the moment, a=
s am I.  (Unless someone else wants to jump in to implement it, which wo=
uld be fine.)

--Larry Garfield