Why don't add "Update/Replace" GroupEvent?

Hi,

It’s me again, I have a question want to ask. In game reactive system, we have to override the GetTrigger method to collect game entity while some components added or removed, but I cannot see the “Update/Replace” event.

I checked the source code, in Group.cs, there is some code holding the updating event:

        /// This is used by the context to manage the group.
        public void UpdateEntity(TEntity entity, int index, IComponent previousComponent, IComponent newComponent) {
            if (_entities.Contains(entity)) {
                if (OnEntityRemoved != null) {
                    OnEntityRemoved(this, entity, index, previousComponent);
                }
                if (OnEntityAdded != null) {
                    OnEntityAdded(this, entity, index, newComponent);
                }
                if (OnEntityUpdated != null) {
                    OnEntityUpdated(
                        this, entity, index, previousComponent, newComponent
                    );
                }
            }
        }

But, in Collector.cs where the OnEntityAdded and OnEntityRemoved delegate were assigned, there’s not any code to set Update/Replace:

        /// Activates the Collector and will start collecting
        /// changed entities. Collectors are activated by default.
        public void Activate() {
            for (int i = 0; i < _groups.Length; i++) {
                var group = _groups[i];
                var groupEvent = _groupEvents[i];
                switch (groupEvent) {
                    case GroupEvent.Added:
                        group.OnEntityAdded -= _addEntityCache;
                        group.OnEntityAdded += _addEntityCache;
                        break;
                    case GroupEvent.Removed:
                        group.OnEntityRemoved -= _addEntityCache;
                        group.OnEntityRemoved += _addEntityCache;
                        break;
                    case GroupEvent.AddedOrRemoved:
                        group.OnEntityAdded -= _addEntityCache;
                        group.OnEntityAdded += _addEntityCache;
                        group.OnEntityRemoved -= _addEntityCache;
                        group.OnEntityRemoved += _addEntityCache;
                        break;
                }
            }
        }

And there is not “Update/Replace” in GroupEvent.cs at all.

So, Is there some design reason or another reason to stop adding “Update/Replace” event in Collector?

Cheers

[yuchting]

@FNGgames I understand your meaning now, that’s to say, I can write CheckDoSomethingStatusSystem like this:

class CheckDoSomethingStatusSystem : IReactiveSystem{
    
    Filter(){
        entity.hasDoSomethingStatus && entity.doSomethingStatus == Done;
    }
    
    GetTrigger(){
        return CreateCollector(GameMatcher.ActionStatus);
    }
    
    Execute(entities){
        entities.foreach(e){
            //if(e.DoSomethingStatus.status == Done){
                e.DoSomethingIdx.idx += 1;
                if(e.DoSomethingIdx.idx >= e.DoSomthingList.list.Count){
                    // all behaviors are executed done
                    e.Destory();
                }else{
                    // add some thing by data
                    Utils.AddComponentForDoSomething(e,e.DoSomthingList.list[e.DoSomethingIdx.idx]);
                }               
            //}
        }
    }
}

and then, if some systems call

e.ReplaceDoSomethingStatus(Done)
or
e.AddDoSomethingStatus(Done)

I will collect these entity and process by this system. Thanks for your explanation, so patient.

I just want to ask another un-resolved problem again, why in Entitas source code Group.cs, there is OnEntityUpdated to handle replace event only, but haven’t realized it and remain a never used variables, it makes me confused.

And more, a method calling ReplaceDoSomethingStatus may raise two different events: Added if hasn’t any Component before or Removed and Added if has one.

Maybe, if you design it one relates one: AddDoSomethingStatus just raises Added event RemoveDoSomethingStatus just raises Removed event ReplaceDoSomethingStatus just raises Replaced event if it has already one, if you haven’t one, it raises Added event.

Is it a better design? Please don’t mind, I just make a suggestion.

@IDNoise thanks for your help, do you mean, you open a issue before, but @sschmid haven’t modified? And he suggests us do:

protected override Collector<GameEntity> GetTrigger(IContext<GameEntity> context) {
    return context.CreateCollector(
        GameMatcher.DoSomethingStatus.Removed(),
        GameMatcher.DoSomethingStatus.Added()
    );
}

rather than:

protected override Collector<GameEntity> GetTrigger(IContext<GameEntity> context) {
    return context.CreateCollector(GameMatcher.DoSomethingStatus.Updated());
}

[RealCosmik]

Perhaps in the filter make sure you state that entity does not have the component so then when the system is triggered it’ll only execute when the entity does not have the component which would be similar to reacting on remove but with replace. Or just actually use the component generated remove method and then just use the add method. I’ve even ran into sometimes where although using replace is just faster to do using removed and then add was just better for my system filtering