protected override IDisposable ReactToPools()
{
var componentType1 = ComponentTypeLookup.GetComponentType(typeof(T1));
var componentType2 = ComponentTypeLookup.GetComponentType(typeof(T2));
var pool1 = ComponentDatabase.GetPoolFor <T1>(componentType1);
var pool2 = ComponentDatabase.GetPoolFor <T2>(componentType2);
var subscriptions = new CompositeDisposable();
pool1.OnPoolExtending.Subscribe(_ => Refresh()).AddTo(subscriptions);
pool2.OnPoolExtending.Subscribe(_ => Refresh()).AddTo(subscriptions);
return(subscriptions);
}