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Date: Wed, 26 Jun 2024 17:09:09 -0600
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Subject: Re: [PHP-DEV] [Initial Feedback] Typed Arrays
To: Rob Landers <rob@bottled.codes>
Cc: internals@lists.php.net
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From: levi.morrison@datadoghq.com (Levi Morrison)

On Wed, Jun 26, 2024 at 3:27=E2=80=AFPM Rob Landers <rob@bottled.codes> wro=
te:
>
>
>
> On Wed, Jun 26, 2024, at 22:56, Casper Langemeijer wrote:
>
>
> On Wed, Jun 26, 2024, at 21:59, Richard Miles wrote:
>
>  I think we should have typed arrays in PHP.
>
>
> Yes! I cannot stand sitting through conference talks on 'generics' that o=
nly talk about 'collections'. This could be solved if we had typed arrays. =
If anything we would get better talks on Generics. :-)
>
> Arrays of a type is one of the last cases where I need docblocks to tell =
my editor about the types.
>
> In my opinion, even if we would have some implementation of generics, hav=
ing typed arrays with a simple syntax would be awesome.
>
> A syntax suggestion:
>
> $array =3D stdClass[];
> class A {
>   public stdClass[] $array;
> }
>
> Adding an invalid array member should throw TypeError.
>
> I know there are way more edge-case situations to think of (for example: =
if class B extends A, $b is of type B[], but holds only A's, can $b be assi=
gned as value of public A[] $a ?)
>
>  Generics or bust.
>
>
> I do not understand the reasoning behind that. Is it because we really wa=
nt generics, but when the 95% use-case is solved we fear that there would n=
ot be enough momentum to get that? I'd love to have generics too, but a ver=
y simple array syntax would in my opinion still add a lot of value, even if=
 we already had generics.
>
>
> You actually just gave me an evil idea on how to get generics in userland=
=E2=80=A6 unfortunately it is bed time as I have an early train to catch in=
 the morning. I will stew on it, but here is the gist:
>
> Create a class that generates a typed collection when accessed via array,=
 such that (new InternalTypedArray)['int'] produces a class that acts like =
an array but only accepts ints.
>
> Using the composer file loading key, load a file that contains:
>
> define('TypedArray', new InternalTypedArray);
>
> You can now use $arr =3D TypedArray['MyType']
>
> Could be interesting and I wouldn=E2=80=99t be surprised if it hasn=E2=80=
=99t been done before.
>
> =E2=80=94 Rob

I have seen variants of this several times. Many will hook into the
autoloader and generate a class/interface definition on-the-fly to
make it work.