Events aka Reactive-UI

Add new Attributes, Data Providers and Code Generators to generate what we know under the name Reactive UI (as explained in this Unite Talk video https://www.youtube.com/watch?v=Phx7IJ3XUzg)

[Event(false)]
public sealed class GameOverComponent : IComponent {
}

[Event(true)]
public sealed class PositionComponent : IComponent {
    public Vector3 value;
}

I plan to generate 2 different events, one that’s independent from entities [Event(false)] and one that’s bound to a specific entity [Event(true)]

public interface IGameOverListener {
    void OnGameOver(bool isGameOver);
}

public sealed class GameOverListenerComponent : IComponent {
    public IGameOverListener value;
}

public sealed class GameOverEventSystem : ReactiveSystem<GameEntity> {

    readonly IGroup<GameEntity> _listsners;

    public GameOverEventSystem(Contexts contexts) : base(contexts.game) {
        _listsners = contexts.game.GetGroup(GameMatcher.GameOverListener);
    }

    protected override ICollector<GameEntity> GetTrigger(IContext<GameEntity> context) {
        return context.CreateCollector(GameMatcher.GameOver.AddedOrRemoved());
    }

    protected override bool Filter(GameEntity entity) {
        return true;
    }

    protected override void Execute(List<GameEntity> entities) {
        foreach (var e in entities) {
            foreach (var listener in _listsners) {
                listener.gameOverListener.value.OnGameOver(e.isGameOver);
            }
        }
    }
}

public interface IPositionListener {
    void OnPosition(Vector3 position);
}

public sealed class PositionListenerComponent : IComponent {
    public IPositionListener value;
}

public sealed class PositionEventSystem : ReactiveSystem<GameEntity> {

    public PositionEventSystem(Contexts contexts) : base(contexts.game) {
    }

    protected override ICollector<GameEntity> GetTrigger(IContext<GameEntity> context) {
        return context.CreateCollector(GameMatcher.Position);
    }

    protected override bool Filter(GameEntity entity) {
        return entity.hasPosition && entity.hasPositionListener;
    }

    protected override void Execute(List<GameEntity> entities) {
        foreach (var e in entities) {
            e.positionListener.value.OnPosition(e.position.value);
        }
    }
}

This is the idea, the implementation might be different once I see it in action.

Discussion and feedback is welcome

[DianeOfTheMoon]

It might be good to change the false/true to something like EventScope.Context/EventScope.Entity to help with readability.

[c0ffeeartc]

Something like [EntityEvent( hasContextsArg = false, hasEntityArg = enumEntityArg.CreationIndex, hasEntityFieldsArgs = true)] or [EntityEvent( argFlags = eContexts | eEntityCreationIndex | eEntityFields]. And everyone gets what he wants. Sounds like a hell of generator 😆