On 28/12/2024 21:56, Juris Evertovskis wrote:
> Hi,
>
>
>
> I would like to propose a new syntax that let’s you implement an interface
> only if it exists.
>
>
>
> `class MyClass extends ?OptionalInterface {}`
>
>
>
> If the `OptionalInterface` exists, the class implements it. If no such
> interface can be found, it is ignored.
>
>
>
> https://wiki.php.net/rfc/optional-interfaces
> <https://wiki.php.net/rfc/optional-interfaces>
>
>
>
> The need to declare compatibility with a certain interface without requiring
> the interface itself comes up when you’re writing code that should work with
> various versions of other libraries or PHP itself and when a library provides
> interoperability with some other library or a PHP extension, but does not
> require it.
>
>
>
> Although this would mainly be used by library developers, the consumers of
> those libraries would also benefit as this syntax would clearly communicate
> the intention of optional interoperability. IDEs and static analysis tools
> could also have easier time with `?OptionalInterface` instead of class
> definitions inside an `if (interface_exists(…)) { … } else {…}`.
>
>
>
> I’ve not entirely sure about the naming as an “optional interface” feels like
> an oxymoron. I’ve also considered names like non-required interfaces,
> conditional interfaces, optional/conditional implementation or even soft
> interfaces/soft implementation. Please let me know if the naming itself
> bothers you.
>
>
>
> Previous discussion: https://externals.io/message/125967
> <https://externals.io/message/125967>
>
> WIP implementation: https://github.com/php/php-src/pull/17288
> <https://github.com/php/php-src/pull/17288>
>
>
>
> Looking forward to your feedback and suggestions!
>
> Juris
>
Hi
I've left some remarks on your PR to help you further with the opcache stuff.
This should fix the tests and answer some questions.
I also left a concern regarding the caching, and in particular I'm thinking
about the inheritance cache. I'll copy it here:
Suppose this scenario:
1. You do a request and an optional interface is not available, this class is
cached without that interface.
2. A future request comes in, and reuses the cache, but since this may be via a
different code path it's possible that the interface is now available. Yet
because the class was cached, this won't implement the interface now even
though it's available at this point in time. I'm not entirely sure if this is a
real problem but it should be checked. I also don't know what assumptions in
the engine this may break.
Kind regards
Niels
