public EntityManager(EntityWorld entityWorld)
{
Debug.Assert(entityWorld != null, "EntityWorld must not be null.");
_uniqueIdToEntities = new Dictionary <long, Entity>();
_removedAndAvailable = new Bag <Entity>();
_componentsByType = new Bag <Bag <IComponent> >();
ActiveEntities = new Bag <Entity>();
_identifierPool = new Bag <int>(4);
RemovedEntitiesRetention = 100;
this._entityWorld = entityWorld;
RemovedComponentEvent += this.EntityManagerRemovedComponentEvent;
}