Re: RFC: Functional Interfaces

Larry Garfield wrote on 19/04/2016 16:21:

Which is why I'm not sure I like that approach, because the place I then call $handler needs to have a conditional in it. There's another RFC that was posted to Twitter but hasn't made it to the list yet that seems to solve this better: https://wiki.php.net/rfc/callable-types

I'm not sure which approach you mean, but in Joe's proposal, you always call $handler as though it was an object implementing the interface; have a look at the ILog example in the RFC. With a typed callable, you can always invoke as $handler(...) will work, but the implementer can't create an object that meets more than one contract, because they can only provide one __invoke method. interface UserEventCallbackInterface {

    public function handleUserEvent(UserEvent $event): boolean;

} interface CommentEventCallbackInterface {

    public function handleCommentEvent(CommentEvent $event): boolean;

} class Logger implements UserEventCallbackInterface, CommentEventCallbackInterface { ... } $logger = new Logger; $simple_user_handler = function(UserEvent $event) implements UserEventCallbackInterface: boolean { ... } In Joe's proposal, $logger and $simple_user_handler can be used interchangeably by calling $handler->handleUserEvent(...); the receiving code doesn't need to do anything special to accept the closure form, because the engine transforms it into the required object. Regards, -- Rowan Collins [IMSoP]