spectrillsky/aether

Unity Event Management System

Aether

Unity Game Engine Event Management System

Feature Overview

• global events with Event or events local to a context with ContextEvent
• no need to remove listeners in OnDestroy for MonoBehaviours
• event queue: all listeners of the original event are executed before any listener of a nested event
• listener predicate conditions
• 3 priority queues per event type
• easy access to the last event of any type

Installation

Install via Add package from git URL in the Package Manager.

Basic Usage

Create a separate class for each event:

public class ExampleEvent : Aether.Event<ExampleEvent>
{
    public readonly int Variable;

    public ExampleEvent(int variable)
    {
        Variable = variable;
    }
}

Add listeners and remove when not needed anymore (they will be automatically removed when the game object gets destroyed):

public class ExampleListener : MonoBehaviour
{
    private void Awake()
    {
        ExampleEvent.AddListener(OnEvent);
    }

    private void OnEvent(ExampleEvent eventData)
    {
        Debug.Log(eventData.Variable);
        ExampleEvent.RemoveListener(OnEvent);
    }
}

Create a new event instance and invoke the event:

public class ExampleInvoker : MonoBehaviour, IPointerClickHandler
{
    public void OnPointerClick(PointerEventData eventData)
    {
        new ExampleEvent(0).Invoke();
    }
}

Good Practices

Use readonly fields or private setter properties as event parameters to prevent listeners from changing them. Use Awake to subscribe to events whenever possible and don't invoke any events until Start to be sure that all listeners have already subscribed.

Order of Execution

If you invoke a new event from an event listener, the original event will execute on all of the remaining listeners first.

Last Event of Type

Use Last property to access the last invoked event of a given type (can be null if the event hasn't been invoked yet).

Context Events

Inherit from ContextEvent instead and pass an additional context parameter when adding a listener and invoking the event. Only listeners with the same context as the event will be executed.

Priority

Pass an additional priority argument when adding a listener to invoke that listener pre or post other listeners for that event.

Predicate

Use predicate field when adding a listener to only invoke the listener if a condition is met.

Event Processed

Subscribe to EventProcessed event to handle all events of any type.