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Date: Thu, 27 Jun 2024 20:11:57 +0200
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Subject: Re: [PHP-DEV] [RFC] Static class
To: Ayesh Karunaratne <ayesh@php.watch>, Bilge <bilge@scriptfusion.com>
Cc: php internals <internals@lists.php.net>
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From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

On 6/24/24 09:53, Ayesh Karunaratne wrote:
> Personally, I think this will be a useful feature. Just like we have
> `readonly` properties and `readonly` classes, I don't see why we can't
> have static methods. I also saw in the draft PR that it does not
> require a lot of changes to the engine to have this.
> 
> I'd like to propose to add some more information and points addressed
> in the RFC. This is of course merely a suggestion, but it's something
> I was thinking when reading the RFC.
> 
>   - Why is it a class-level flag and not an attribute (similar to the
> `#[Override]` attribute in PHP 8.3) ?

To quote myself from the #[\Override] RFC:

> This RFC proposes an attribute instead of a keyword, because contrary to other modifiers (e.g. visibility) that are part of the method signature, the attribute does not affect behavior or compatibility for users that further extend a given class and neither does it affect users that call the method. It is purely an assistance to the author of a given class.
> 

Marking a class as 'static' *does* affect how the class may be used and 
thus the static-ness is part of the public API. Therefore it should be a 
keyword. Everything else would also be inconsistent with final classes 
effectively making all members final and readonly classes making all 
members readonly.

>   - Can a subclass extend a static parent class without using the
> `static` keyword in the subclass? This will avoid a lot of BC issues
> if a library decides to declare classes as static.

It should not. See: readonly classes. I also believe that static classes 
should be implictly final. Given that no objects of such a class can 
exist, they cannot be exchanged by a different class anyways and 
inheritance is not meant for code reuse.

Best regards
Tim Düsterhus