Re: First class callable syntax for instance methods

On Thu, Apr 13, 2023 at 6:00 AM Eugene Sidelnyk <zsidelnik@gmail.com> wrote: > > Hello, internals! I just want to share some thoughts with you regarding > what could be improved in the first class callable syntax. > > It is already possible to create Callable from a static method: > > ``` > class Foo { > public static function staticmethod() {} > } > > $c = Foo::staticmethod(...); > ``` > > It would be a great pleasure to have the ability to wrap the instance > method the same way. One particular use case for this could be when there's > an array of items and it is necessary to call some getter-method on all of > them. > > ``` > class Verification > { > public function __construct(private string $id) {} > > public function getId(): string > { > return $this->id; > } > } > > $items = [new Verification('1-2-3-4')]; > > array_map(Verification::getId(...), $items); > > // previous line is an equivalent of this > array_map(static fn (Verification $v) => $v->getId(), $items); > ``` > > Currently this syntax fails in run-time rather than compile-time. > > ``` > PHP Fatal error: Uncaught Error: Non-static method Verification::getId() > cannot be called statically in /opt/scratches/scratch_439.php:21 > ``` > > Please, let me know what you think about it. > > Best regards, Yeven Hello, This has been brought up a couple of times, but I can't seem to find it. I don't think something like this is possible with the current implementation of first-class-callables (it would need a major refactor). Currently adding the callable bit like func(...) is roughly the same as just writing a string 'func' and passing that around (IIRC, that's literally what it gets turned to after parsing). The only difference over using a string, is that there is some validation to check that it is actually a function you can call. Basically, there's currently no way to do something like what you suggest in the engine, which makes it quite a big feature. That being said, we shouldn't be afraid of doing hard things, but it would be a lot of work for saving just a few characters of typing every now and then. Perhaps it would be easier after partial application could be implemented (latest discussion here: https://externals.io/message/119678#119678), or maybe someone else has some better ideas or thoughts. Cheers, Rob Landers Utrecht, Netherlands