What is the reason for the event package to use donburi.World instead of *ecs.ECS in subscriptions?

[soockee]

Hello 👋

What is the reason for the event package to use donburi.World instead of *ecs.ECS on the subscription?

If an event is handled by a function (Subscriber), than the donburi.World argument is available.
For example, an event handler is supposed to create an entity in the world, the following function would do the deed.

func (a *archetype) SpawnInWorld(world donburi.World, cs ...donburi.IComponentType) *donburi.Entry {
	// where is it located? Is it placed in a layer?
        e := world.Entry(world.Create(
		append(a.components, cs...)...,
	)) 
	return e
}

func eventHandler(w donburi.World, e *event.Collide){
   archetype.Settings.SpawnInWorld()
} 

I was wondering that the layers systems can not be utilized that easily this way. The following shows a entity creating with the ecs, that contains the world naturally.

func (a *archetype) Spawn(ecs *ecs.ECS, cs ...donburi.IComponentType) *donburi.Entry {
	e := ecs.World.Entry(ecs.Create(
		layers.Default,
		append(a.components, cs...)...,
	))
	return e
}

func eventHandler(w donburi.World, e *event.Collide){
   // now located in the default layer
   archetype.Settings.Spawn()
} 

So I would appreciate a reasoning for this design choice. :)

Best regards,
Soockee

[yohamta]

Hello, the ecs package was an experimental feature and that's why the event package use World instance. I think we can improve the event package to allow us to use an ecs or a world instance (using Generics or any). I'd very much welcome a contribution if anyone wants to work on it.