Merge pull request #22 from SemihBudak/master

Added id overload for EntityCollection.CreateEntity

Author: grofit

src/EcsRx/Collections/Entity/EntityCollection.cs

@@ -58,9 +58,12 @@ public void SubscribeToEntity(IEntity entity)
         public void UnsubscribeFromEntity(int entityId)
         { EntitySubscriptions.RemoveAndDispose(entityId); }
 
-        public IEntity CreateEntity(IBlueprint blueprint = null)
+        public IEntity CreateEntity(IBlueprint blueprint = null, int? id = null)
         {
-            var entity = EntityFactory.Create(null);
+            if (id.HasValue && EntityLookup.Contains(id.Value))
+            { throw new InvalidOperationException("id already exists"); }
+
+            var entity = EntityFactory.Create(id);
 
             EntityLookup.Add(entity);
             _onEntityAdded.OnNext(new CollectionEntityEvent(entity));

src/EcsRx/Collections/Entity/IEntityCollection.cs

@@ -14,14 +14,15 @@ public interface IEntityCollection : IReadOnlyList<IEntity>, INotifyingEntityCol
         /// Name of the collection
         /// </summary>
         int Id { get; }
-        
+
         /// <summary>
         /// This will create and return a new entity.
         /// If required you can pass in a blueprint which the created entity will conform to
         /// </summary>
         /// <param name="blueprint">Optional blueprint to use for the entity (defaults to null)</param>
+        /// <param name="id">Id to use for the entity (defaults to null, meaning it'll automatically get the next available id)</param>
         /// <returns></returns>
-        IEntity CreateEntity(IBlueprint blueprint = null);
+        IEntity CreateEntity(IBlueprint blueprint = null, int? id = null);
 
         /// <summary>
         /// This will add an existing entity into the group, it is mainly used for pre-made