Idiomatic Go - biggest breaking change yet about ecs HOT 4 CLOSED

// Create the entity
e := &MyEntity{}

// Loop over all systems. This way we loop only once, and add it to all systems we like
for _, system := range systems {
    switch sys := system.(type) {
        case *RenderSystem:
            sys.Add(&e.BasicEntity, &e.SpaceComponent, &e.RenderComponent)
        case *MouseSystem:
            sys.Add(&e.BasicEntity, &e.SpaceComponent, &e.MouseComponent)
    }
}

type AnimationSystem struct {
    ecs.LinearSystem
}

func (a *AnimationSystem) New(*ecs.World) {}

func (*AnimationSystem) Type() string { return "AnimationSystem" }
func (*AnimationSystem) Pre()         {}
func (*AnimationSystem) Post()        {}

func (a *AnimationSystem) UpdateEntity(entity *ecs.Entity, dt float32) {
    var (
        ac *AnimationComponent
        r  *RenderComponent
        ok bool
    )

    if ac, ok = entity.ComponentFast(ac).(*AnimationComponent); !ok {
        return
    }
    if r, ok = entity.ComponentFast(r).(*RenderComponent); !ok {
        return
    }

    ac.change += dt
    if ac.change >= ac.Rate {
        ac.NextFrame()
        r.SetDrawable(ac.Cell())
    }
}

type animationEntity struct {
    *ecs.BasicEntity
    *AnimationComponent
    *RenderComponent
}

type AnimationSystem struct {
    entities []animationSystemEntity
}

func (a *AnimationSystem) Add(e *ecs.BasicEntity, anim *AnimationComponent, rend *RenderComponent) {
    a.entities = append(a.entities, []animationEntity{e, anim, rend})
}

func (a *AnimationSystem) Remove(basic ecs.BasicEntity) {
    delete := -1
    for index, e := range a.entities {
        if e.ID() == basic.ID() {
            delete = index
            break
        }
    }
    if delete >= 0 {
        a.entities = append(a.entities[:delete], a.entities[delete+1:]...)
    }
}

func (a *AnimationSystem) Update(dt float32) {
    for _, e := range a.entities {
        e.AnimationComponent.change += dt
        if e.AnimationComponent.change >= e.AnimationComponent.Rate {
            e.AnimationComponent.NextFrame()
            e.RenderComponent.SetDrawable(e.AnimationComponent.Cell())
        }
    }
}