listenable Interfaces/Functions Should Pass this as the First Argument

Development Programming & Scripting Verse
, ,
1

Trying to use listenables to create device interactions that are not 1:1 (1 device directly bound to another device) is extremely painful right now.

For instance, let’s say you want to monitor the 40 vehicle spawners in your level to respawn a vehicle whenever a player exits a vehicle.

AgentExitsVehicleEvent tells you when an agent exits the vehicle, but it doesn’t give you the vehicle_spawner_device that called the event. So now you have to write your own little tracking system to map vehicle spawners to players😩

This is the same situation for literally every device in the game e.g.:

  • Vending machines/ItemSpawnedEvent
  • trigger_device/TriggeredEvent
  • trick_tile_device/ActivatedEvent
  • tracker_device/CompleteEvent
  • timer_device/SuccessEvent

This was the same situation back when UE4’s Hit/Overlap events didn’t return the primitive component and actor that was firing the event. Luckily this was remedied. We need a similar standard for fortnite listenables, where perhaps the first argument is always this :pray:

1 Like
2

I agree more info passed would be extremally helpful. But for now, you can create a callback handler class that passes the additional references you need to what device triggered the event. Something like this: (untested!)

# custom callback handler that passes the device that triggered the event
CustomCallbackHandler := class():
    Manager : test_callback_device 
    Device : vehicle_spawner_device
    HandlerFunction(Agent:agent):void=
        Manager.OnEventTriggered(Agent, Device)

test_callback_device := class(creative_device):

    @editable
    Devices : []vehicle_spawner_device = array{}

    OnBegin<override>()<suspends>:void=
        for(X -> Device : Devices):
            # pass reference to callback 
Device.AgentExitsVehicleEvent.Subscribe(CustomCallbackHandler{Manager:=Self, Device:=Device}.HandlerFunction)

    OnEventTriggered(Agent:agent, Device:vehicle_spawner_device):void=
        # do something....
3 Likes
3

wooooooowww, thank you for this!

:exploding_head: I had no idea you could construct a class, initialize its members and return a pointer to the instantiated class function all in one blow. This expanded my mind and made my implementation trivial.

What is the advantage of this syntax? The X seems unused. Force of habit for more complex loops?

1 Like
4

The X gives you the index in the loop, but yes unused in this example, just out of habit. :wink:

1 Like