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]
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