[EventDispatcher] Listeners per events which implement some interface

[alebedev80]

Description

I need event subscriber which listen any event which implements some interface.

Example

The LoggableEventSubscriber::onLoggableEvent() will be called per EventFoo and EventBar

interface LoggableEvent {}

class EventFoo implements LoggableEvent{}
class EventBar implements LoggableEvent{}
class EventBaz {}

final readonly class LoggableEventSubscriber implements EventSubscriberInterface
{

    public static function getSubscribedEvents(): array
    {
        return [
            LoggableEvent::class => [['onLoggableEvent, 1000]],
        ];
    }

   public function onLoggableEvent() {
       ....
   }

[stof]

Supporting that would probably have a non-negligeable performance impact (for all users of the components, not just when this feature is used) because this requires changing the loading of listeners to not be a O(1) lookup in a hashmap anymore.

[alebedev80]

@stof of course, the performance of such a dispatcher will be worse, but the organization of the code and its support for some tasks will be greatly improved. I think it makes sense to make a separate class of the dispatcher, which the user will connect independently if necessary.

[abidkhan484]

Dear Concern,

If the feature will be accepted by the maintainers, I would like to try to implement the feature.

Regards,
Abid

[mihai-stancu]

+1

[xabbuh]

Given that the proposed event dispatcher would have a worse performance compared to the optimized one we already have I would be rather reluctant to add this one to the core. IMO such a class would fit nicely in a third-party package that could make the upsides and downsides of the class compared to Symfony's one quite clear.

[carsonbot]

Thank you for this suggestion.
There has not been a lot of activity here for a while. Would you still like to see this feature?

[derrabus]

I think, @stof and @xabbuh gave us very good reasons to close this feature request.