module Athena::EventDispatcher::EventListenerInterface

Overview

Interface for event listeners.

Listeners are defined by including this module.

An event can be listened for by defining #call(event : AED::Event, dispatcher : AED::EventDispatcherInterface) : Nil. The first argument should be typed to the specific AED::Event instance that the method should listen on. Multiple methods can be defined to handle multiple events within the same listener.

Implementors must also define self.subscribed_events : AED::SubscribedEvents that represents the events that self's methods are listening on. The value of the hash is the priority of the listener. The higher the value the sooner that listener method gets executed.

Implementors can also define initializers if external dependencies are required for handling the event. However, AED::EventDispatcher#new(listeners : Array(EventListenerInterface)) must be used to register self, either with DI, or provided manually.

struct TestListener
  include AED::EventListenerInterface

  def self.subscribed_events : AED::SubscribedEvents
    AED::SubscribedEvents{
      HttpRequestEvent => 0,
      ExceptionEvent   => 4,
    }
  end

  def call(event : HttpRequestEvent, dispatcher : AED::EventDispatcherInterface) : Nil
    # Do something with the `HttpRequestEvent` and/or dispatcher
  end

  def call(event : ExceptionEvent, dispatcher : AED::EventDispatcherInterface) : Nil
    # Do something with the `ExceptionEvent` and/or dispatcher
  end
end

Defined in:

event_listener_interface.cr

Class Method Summary

• .subscribed_events : AED::SubscribedEvents

  Returns the AED::Events that self is listening on, along with the listener priority of each event.

Instance Method Summary

• #call(event : AED::Event, dispatcher : AED::EventDispatcherInterface) : Nil

  Example method for listening on a specific event.

Class Method Detail

Instance Method Detail