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Date: Mon, 8 May 2023 10:01:57 +0200
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To: internals <internals@lists.php.net>
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Subject: Re: Limit write access to object function parameters
From: olleharstedt@gmail.com (=?UTF-8?Q?Olle_H=C3=A4rstedt?=)

2023-05-06 12:55 GMT+02:00, Olle H=C3=A4rstedt <olleharstedt@gmail.com>:
> Heyo internalitos,
>
> I was thinking of having the possibility to use `readonly` (or any
> other keyword) to make a function argument behave as if it was a
> readonly object.
>
>     class Point
>     {
>       public int $x;
>       public int $y;
>     }
>     function doThing(readonly Point $p)
>     {
>       $p->x =3D 10;  // Not allowed
>     }
>
> In C# it's called in/out/ref types:
> https://www.pluralsight.com/guides/csharp-in-out-ref-parameters
>
> The main use-case is to not give away more access than you have to,
> and being able to state your intent in the function signature.
>
> Another alternative would be to allow properties in interfaces, and
> then define a readonly-like interface:
>
>     interface ReadonlyPoint
>     {
>       public readonly int $x;
>       public readonly int $y;
>     }
>     function doThing(ReadonlyPoint $p)
>     {
>       $p->x =3D 10;  // Not allowed
>     }
>
> No idea about practical feasability.
>
> Since arrays are value types, they're not really relevant for this
> suggestion. Same goes for string, int, etc.
>
> Regards
> Olle

Also related is Object.freeze from JS (I was told):
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Ob=
jects/Object/freeze

Olle