diff --git a/Svelto.ECS/DataStructures/TypeSafeDictionary.cs b/Svelto.ECS/DataStructures/TypeSafeDictionary.cs
index d852218..540d77f 100644
--- a/Svelto.ECS/DataStructures/TypeSafeDictionary.cs
+++ b/Svelto.ECS/DataStructures/TypeSafeDictionary.cs
@@ -144,7 +144,7 @@ namespace Svelto.ECS.Internal
             return new TypeSafeDictionary<TValue>();
         }
         
-        public bool ExecuteOnEntityView<W>(int entityGidEntityId, ref W value, ActionRef<TValue, W> action)
+        public bool ExecuteOnEntityView<W>(int entityGidEntityId, ref W value, EntityAction<TValue, W> action)
         {
             uint findIndex;
             if (FindIndex(entityGidEntityId, out findIndex))
@@ -157,7 +157,7 @@ namespace Svelto.ECS.Internal
             return false;
         }
         
-        public bool ExecuteOnEntityView(int entityGidEntityId, ActionRef<TValue> action)
+        public bool ExecuteOnEntityView(int entityGidEntityId, EntityAction<TValue> action)
         {
             uint findIndex;
             if (FindIndex(entityGidEntityId, out findIndex))
diff --git a/Svelto.ECS/EntitiesDB.cs b/Svelto.ECS/EntitiesDB.cs
index 175e84a..aa9fa6d 100644
--- a/Svelto.ECS/EntitiesDB.cs
+++ b/Svelto.ECS/EntitiesDB.cs
@@ -6,7 +6,7 @@ using Svelto.Utilities;
 
 namespace Svelto.ECS.Internal
 {
-    class entitiesDB : IEntitiesDB
+    partial class entitiesDB : IEntitiesDB
     {
         internal entitiesDB(Dictionary<int, Dictionary<Type, ITypeSafeDictionary>> groupEntityViewsDB,
             Dictionary<Type, FasterDictionary<int, ITypeSafeDictionary>> groupedGroups)
@@ -90,197 +90,6 @@ namespace Svelto.ECS.Internal
             return entityView;
         }
 
-        public void ExecuteOnEntity<T, W>(EGID entityGID, ref W value, ActionRef<T, W> action) where T : IEntityStruct
-        {
-            TypeSafeDictionary<T> casted;
-            if (QueryEntitySafeDictionary(entityGID.groupID, out casted))
-            {
-                if (casted != null)
-                    if (casted.ExecuteOnEntityView(entityGID.entityID, ref value, action) == true)
-                        return;
-            }
-
-            throw new EntitiesDBException("Entity not found id: ".FastConcat(entityGID.entityID).FastConcat(" groupID: ").FastConcat(entityGID.groupID));
-        }
-        
-        public void ExecuteOnEntity<T>(EGID entityGID, ActionRef<T> action) where T : IEntityStruct
-        {
-            TypeSafeDictionary<T> casted;
-            if (QueryEntitySafeDictionary(entityGID.groupID, out casted))
-            {
-                if (casted != null)
-                    if (casted.ExecuteOnEntityView(entityGID.entityID, action) == true)
-                        return;
-            }
-
-            throw new EntitiesDBException("Entity not found id: ".FastConcat(entityGID.entityID).FastConcat(" groupID: ").FastConcat(entityGID.groupID));
-        }
-
-        public void ExecuteOnEntity<T>(int id, ActionRef<T> action) where T : IEntityStruct
-        {
-            ExecuteOnEntity(new EGID(id, ExclusiveGroup.StandardEntitiesGroup), action);
-        }
-
-        public void ExecuteOnEntity<T>(int id, int groupid, ActionRef<T> action) where T : IEntityStruct
-        {
-            ExecuteOnEntity(new EGID(id, groupid), action);
-        }
-
-        public void ExecuteOnEntity<T, W>(int id, ref W value, ActionRef<T, W> action) where T : IEntityStruct
-        {
-            ExecuteOnEntity(new EGID(id, ExclusiveGroup.StandardEntitiesGroup), ref value, action);
-        }
-
-        public void ExecuteOnEntity<T, W>(int id, int groupid, ref W value, ActionRef<T, W> action) where T : IEntityStruct
-        {
-            ExecuteOnEntity(new EGID(id, groupid), ref value, action);
-        }
-
-        public void ExecuteOnEntities<T>(int groupID, ActionRef<T> action) where T : IEntityStruct
-        {
-            int                   count;
-            TypeSafeDictionary<T> typeSafeDictionary;
-            if (QueryEntitySafeDictionary(@groupID, out typeSafeDictionary) == false) return;
-            
-            var entities = typeSafeDictionary.GetFasterValuesBuffer(out count);
-            
-            for (var i = 0; i < count; i++)
-                action(ref entities[i]);
-            
-            SafetyChecks(typeSafeDictionary, count);
-        }
-
-        static void SafetyChecks<T>(TypeSafeDictionary<T> typeSafeDictionary, int count) where T : IEntityStruct
-        {
-            if (typeSafeDictionary.Count != count)
-                throw new EntitiesDBException("Entities cannot be swapped or removed during an iteration");
-        }
-
-        public void ExecuteOnEntities<T>(ActionRef<T> action) where T : IEntityStruct
-        {
-            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, action);
-        }
-
-        public void ExecuteOnEntities<T, W>(int groupID, ref W value, ActionRef<T, W> action) where T : IEntityStruct
-        {
-            int                   count;
-            TypeSafeDictionary<T> typeSafeDictionary;
-            if (QueryEntitySafeDictionary(@groupID, out typeSafeDictionary) == false) return;
-            
-            var entities = typeSafeDictionary.GetFasterValuesBuffer(out count);
-            
-            for (var i = 0; i < count; i++)
-                action(ref entities[i], ref value);
-            
-            SafetyChecks(typeSafeDictionary, count);
-        }
-
-        public void ExecuteOnEntities<T, W>(ref W value, ActionRef<T, W> action) where T : IEntityStruct
-        {
-            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, ref value, action);
-        }
-        
-        public void ExecuteOnEntities<T, T1, W>(W value, ActionRef<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct
-        {
-            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, ref value, action);
-        }
-
-        public void ExecuteOnAllEntities<T>(ActionRef<T> action) where T : IEntityStruct
-        {
-            var type = typeof(T);
-            FasterDictionary<int, ITypeSafeDictionary> dic;
-            if (_groupedGroups.TryGetValue(type, out dic))
-            {
-                int count;
-                var typeSafeDictionaries = dic.GetFasterValuesBuffer(out count);
-                for (int j = 0; j < count; j++)
-                {
-                    int innerCount;
-                    var typeSafeDictionary = typeSafeDictionaries[j];
-                    var casted             = typeSafeDictionary as TypeSafeDictionary<T>;
-                    
-                    var entities = casted.GetFasterValuesBuffer(out innerCount);
-
-                    for (int i = 0; i < innerCount; i++)
-                        action(ref entities[i]);
-                    
-                    SafetyChecks(casted, count);
-                }
-            }
-        }
-
-        public void ExecuteOnAllEntities<T, W>(ref W value, ActionRef<T, W> action) where T : IEntityStruct
-        {
-            var  type = typeof(T);
-            FasterDictionary<int, ITypeSafeDictionary> dic;
-            if (_groupedGroups.TryGetValue(type, out dic))
-            {
-                int count;
-                var typeSafeDictionaries = dic.GetFasterValuesBuffer(out count);
-                for (int j = 0; j < count; j++)
-                {
-                    int innerCount;
-                    var typeSafeDictionary = typeSafeDictionaries[j];
-                    var casted   = typeSafeDictionary as TypeSafeDictionary<T>;
-                    
-                    var entities = casted.GetFasterValuesBuffer(out innerCount);
-
-                    for (int i = 0; i < innerCount; i++)
-                        action(ref entities[i], ref value);
-                    
-                    SafetyChecks(casted, count);
-                }
-            }
-        }
-
-        public void ExecuteOnEntities<T, T1>(int group, ActionRef<T, T1> action) where T : IEntityStruct where T1 : IEntityStruct
-        {
-            int count;
-            TypeSafeDictionary<T> typeSafeDictionary;
-            if (QueryEntitySafeDictionary(@group, out typeSafeDictionary) == false) return;
-            
-            var entities  = typeSafeDictionary.GetFasterValuesBuffer(out count);
-
-            EGIDMapper<T1> map = QueryMappedEntities<T1>(group);
-            
-            for (var i = 0; i < count; i++)
-            {
-                uint index;
-                action(ref entities[i], ref map.entities(entities[i].ID, out index)[index]);
-            }
-
-            SafetyChecks(typeSafeDictionary, count);
-        }
-        
-        public void ExecuteOnEntities<T, T1, W>(int group, ref W value, ActionRef<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct
-        {
-            int                   count;
-            TypeSafeDictionary<T> typeSafeDictionary;
-            if (QueryEntitySafeDictionary(@group, out typeSafeDictionary) == false) return;
-            
-            var entities = typeSafeDictionary.GetFasterValuesBuffer(out count);
-
-            EGIDMapper<T1> map = QueryMappedEntities<T1>(group);
-            
-            for (var i = 0; i < count; i++)
-            {
-                uint index;
-                action(ref entities[i], ref map.entities(entities[i].ID, out index)[index], ref value);
-            }
-
-            SafetyChecks(typeSafeDictionary, count);
-        }
-
-        public void ExecuteOnEntities<T, T1>(ActionRef<T, T1> action) where T : IEntityStruct where T1 : IEntityStruct
-        {
-            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, action);
-        }
-        
-        public void ExecuteOnEntities<T, T1, W>(ref W value, ActionRef<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct
-        {
-            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, ref value, action);
-        }
-
         public bool Exists<T>(EGID entityGID) where T : IEntityStruct
         {
             TypeSafeDictionary<T> casted;
@@ -347,6 +156,14 @@ namespace Svelto.ECS.Internal
             
             return true;
         }
+        
+        static void SafetyChecks<T>(TypeSafeDictionary<T> typeSafeDictionary, int count) where T : IEntityStruct
+        {
+#if DEBUG            
+            if (typeSafeDictionary.Count != count)
+                throw new EntitiesDBException("Entities cannot be swapped or removed during an iteration");
+#endif            
+        }
 
         static ReadOnlyCollectionStruct<T> RetrieveEmptyEntityViewList<T>()
         {
diff --git a/Svelto.ECS/EntityViewBuilder.cs b/Svelto.ECS/EntityBuilder.cs
similarity index 98%
rename from Svelto.ECS/EntityViewBuilder.cs
rename to Svelto.ECS/EntityBuilder.cs
index 0b91ea7..18f0168 100644
--- a/Svelto.ECS/EntityViewBuilder.cs
+++ b/Svelto.ECS/EntityBuilder.cs
@@ -16,7 +16,7 @@ namespace Svelto.ECS
             _initializer = default(T);
 
 #if DEBUG && !PROFILER
-            if (needsReflection == false && typeof(T) != typeof(EntityInfoView))
+            if (needsReflection == false)
             {
                 CheckFields(typeof(T));
             }
diff --git a/Svelto.ECS/EntityInfoView.cs b/Svelto.ECS/EntityInfoView.cs
deleted file mode 100644
index 419d531..0000000
--- a/Svelto.ECS/EntityInfoView.cs
+++ /dev/null
@@ -1,9 +0,0 @@
-namespace Svelto.ECS
-{
-    public struct EntityInfoView : IEntityStruct
-    {
-        public EGID ID { get; set; }
-        
-        public IEntityBuilder[] entityToBuild;
-    }
-}
\ No newline at end of file
diff --git a/Svelto.ECS/ExecuteOnEntitiesDB.cs b/Svelto.ECS/ExecuteOnEntitiesDB.cs
new file mode 100644
index 0000000..5b35f46
--- /dev/null
+++ b/Svelto.ECS/ExecuteOnEntitiesDB.cs
@@ -0,0 +1,212 @@
+using Svelto.DataStructures.Experimental;
+using Svelto.Utilities;
+
+namespace Svelto.ECS.Internal
+{
+    partial class entitiesDB
+    {
+        public void ExecuteOnEntity<T, W>(EGID entityGID, ref W value, EntityAction<T, W> action) where T : IEntityStruct
+        {
+            TypeSafeDictionary<T> casted;
+            if (QueryEntitySafeDictionary(entityGID.groupID, out casted))
+            {
+                if (casted != null)
+                    if (casted.ExecuteOnEntityView(entityGID.entityID, ref value, action) == true)
+                        return;
+            }
+
+            throw new EntitiesDBException("Entity not found id: "
+                                         .FastConcat(entityGID.entityID).FastConcat(" groupID: ")
+                                         .FastConcat(entityGID.groupID));
+        }
+
+        public void ExecuteOnEntity<T>(EGID entityGID, EntityAction<T> action) where T : IEntityStruct
+        {
+            TypeSafeDictionary<T> casted;
+            if (QueryEntitySafeDictionary(entityGID.groupID, out casted))
+            {
+                if (casted != null)
+                    if (casted.ExecuteOnEntityView(entityGID.entityID, action) == true)
+                        return;
+            }
+
+            throw new EntitiesDBException("Entity not found id: "
+                                         .FastConcat(entityGID.entityID).FastConcat(" groupID: ")
+                                         .FastConcat(entityGID.groupID));
+        }
+
+        public void ExecuteOnEntity<T>(int id, EntityAction<T> action) where T : IEntityStruct
+        {
+            ExecuteOnEntity(new EGID(id, ExclusiveGroup.StandardEntitiesGroup), action);
+        }
+
+        public void ExecuteOnEntity<T>(int id, int groupid, EntityAction<T> action) where T : IEntityStruct
+        {
+            ExecuteOnEntity(new EGID(id, groupid), action);
+        }
+
+        public void ExecuteOnEntity<T, W>(int id, ref W value, EntityAction<T, W> action) where T : IEntityStruct
+        {
+            ExecuteOnEntity(new EGID(id, ExclusiveGroup.StandardEntitiesGroup), ref value, action);
+        }
+
+        public void ExecuteOnEntity<T, W>(int id, int groupid, ref W value, EntityAction<T, W> action)
+            where T : IEntityStruct
+        {
+            ExecuteOnEntity(new EGID(id, groupid), ref value, action);
+        }
+        
+        //----------------------------------------------------------------------------------------------------------
+
+        public void ExecuteOnEntities<T>(int groupID, EntitiesAction<T> action) where T : IEntityStruct
+        {
+            int                   count;
+            TypeSafeDictionary<T> typeSafeDictionary;
+            if (QueryEntitySafeDictionary(@groupID, out typeSafeDictionary) == false) return;
+
+            var entities = typeSafeDictionary.GetFasterValuesBuffer(out count);
+
+            for (var i = 0; i < count; i++)
+                action(ref entities[i], i);
+
+            SafetyChecks(typeSafeDictionary, count);
+        }
+
+        public void ExecuteOnEntities<T>(EntitiesAction<T> action) where T : IEntityStruct
+        {
+            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, action);
+        }
+
+        public void ExecuteOnEntities<T, W>(int groupID, ref W value, EntitiesAction<T, W> action) where T : IEntityStruct
+        {
+            int                   count;
+            TypeSafeDictionary<T> typeSafeDictionary;
+            if (QueryEntitySafeDictionary(@groupID, out typeSafeDictionary) == false) return;
+
+            var entities = typeSafeDictionary.GetFasterValuesBuffer(out count);
+
+            for (var i = 0; i < count; i++)
+                action(ref entities[i], ref value, i);
+
+            SafetyChecks(typeSafeDictionary, count);
+        }
+
+        public void ExecuteOnEntities<T, W>(ref W value, EntitiesAction<T, W> action) where T : IEntityStruct
+        {
+            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, ref value, action);
+        }
+
+        public void ExecuteOnEntities<T, T1, W>(W value, EntitiesAction<T, T1, W> action)
+            where T : IEntityStruct where T1 : IEntityStruct
+        {
+            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, ref value, action);
+        }
+
+        public void ExecuteOnEntities<T, T1>(int group, EntitiesAction<T, T1> action)
+            where T : IEntityStruct where T1 : IEntityStruct
+        {
+            int                   count;
+            TypeSafeDictionary<T> typeSafeDictionary;
+            if (QueryEntitySafeDictionary(@group, out typeSafeDictionary) == false) return;
+
+            var entities = typeSafeDictionary.GetFasterValuesBuffer(out count);
+
+            EGIDMapper<T1> map = QueryMappedEntities<T1>(@group);
+
+            for (var i = 0; i < count; i++)
+            {
+                uint index;
+                action(ref entities[i], ref map.entities(entities[i].ID, out index)[index], i);
+            }
+
+            SafetyChecks(typeSafeDictionary, count);
+        }
+
+        public void ExecuteOnEntities<T, T1, W>(int group, ref W value, EntitiesAction<T, T1, W> action)
+            where T : IEntityStruct where T1 : IEntityStruct
+        {
+            int                   count;
+            TypeSafeDictionary<T> typeSafeDictionary;
+            if (QueryEntitySafeDictionary(@group, out typeSafeDictionary) == false) return;
+
+            var entities = typeSafeDictionary.GetFasterValuesBuffer(out count);
+
+            EGIDMapper<T1> map = QueryMappedEntities<T1>(@group);
+
+            for (var i = 0; i < count; i++)
+            {
+                uint index;
+                action(ref entities[i], ref map.entities(entities[i].ID, out index)[index], ref value, i);
+            }
+
+            SafetyChecks(typeSafeDictionary, count);
+        }
+
+        public void ExecuteOnEntities<T, T1>(EntitiesAction<T, T1> action) where T : IEntityStruct where T1 : IEntityStruct
+        {
+            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, action);
+        }
+
+        public void ExecuteOnEntities<T, T1, W>(ref W value, EntitiesAction<T, T1, W> action)
+            where T : IEntityStruct where T1 : IEntityStruct
+        {
+            ExecuteOnEntities(ExclusiveGroup.StandardEntitiesGroup, ref value, action);
+        }
+        
+        //-----------------------------------------------------------------------------------------------------------
+        
+        public void ExecuteOnAllEntities<T>(EntityAction<T> action) where T : IEntityStruct
+        {
+            var                                        type = typeof(T);
+            FasterDictionary<int, ITypeSafeDictionary> dic;
+
+            if (_groupedGroups.TryGetValue(type, out dic))
+            {
+                int count;
+                var typeSafeDictionaries = dic.GetFasterValuesBuffer(out count);
+
+                for (int j = 0; j < count; j++)
+                {
+                    int innerCount;
+                    var typeSafeDictionary = typeSafeDictionaries[j];
+                    var casted             = typeSafeDictionary as TypeSafeDictionary<T>;
+
+                    var entities = casted.GetFasterValuesBuffer(out innerCount);
+
+                    for (int i = 0; i < innerCount; i++)
+                        action(ref entities[i]);
+
+                    SafetyChecks(casted, count);
+                }
+            }
+        }
+
+        public void ExecuteOnAllEntities<T, W>(ref W value, EntityAction<T, W> action) where T : IEntityStruct
+        {
+            var                                        type = typeof(T);
+            FasterDictionary<int, ITypeSafeDictionary> dic;
+
+            if (_groupedGroups.TryGetValue(type, out dic))
+            {
+                int count;
+                var typeSafeDictionaries = dic.GetFasterValuesBuffer(out count);
+
+                for (int j = 0; j < count; j++)
+                {
+                    int innerCount;
+                    var typeSafeDictionary = typeSafeDictionaries[j];
+                    var casted             = typeSafeDictionary as TypeSafeDictionary<T>;
+
+                    var entities = casted.GetFasterValuesBuffer(out innerCount);
+
+                    for (int i = 0; i < innerCount; i++)
+                        action(ref entities[i], ref value);
+
+                    SafetyChecks(casted, count);
+                }
+            }
+        }
+
+
+    }
+}
\ No newline at end of file
diff --git a/Svelto.ECS/IEntitiesDB.cs b/Svelto.ECS/IEntitiesDB.cs
index a8f7940..c5571da 100644
--- a/Svelto.ECS/IEntitiesDB.cs
+++ b/Svelto.ECS/IEntitiesDB.cs
@@ -1,5 +1,4 @@
 using Svelto.DataStructures;
-using Svelto.Utilities;
 
 namespace Svelto.ECS
 {
@@ -60,10 +59,10 @@ namespace Svelto.ECS
         /// <param name="egid"></param>
         /// <param name="action"></param>
         /// <typeparam name="T"></typeparam>
-        void ExecuteOnEntities<T>(int groupID, ActionRef<T> action) where T : IEntityStruct;
-        void ExecuteOnEntities<T>(ActionRef<T> action) where T : IEntityStruct;
-        void ExecuteOnEntities<T, W>(int groupID, ref W value, ActionRef<T, W> action) where T : IEntityStruct;
-        void ExecuteOnEntities<T, W>(ref W value, ActionRef<T, W> action) where T : IEntityStruct;
+        void ExecuteOnEntities<T>(int groupID, EntitiesAction<T> action) where T : IEntityStruct;
+        void ExecuteOnEntities<T>(EntitiesAction<T> action) where T : IEntityStruct;
+        void ExecuteOnEntities<T, W>(int groupID, ref W value, EntitiesAction<T, W> action) where T : IEntityStruct;
+        void ExecuteOnEntities<T, W>(ref W value, EntitiesAction<T, W> action) where T : IEntityStruct;
         /// <summary>
         /// This specialized version allows to execute actions on multiple entity views or entity structs
         /// Safety checks are in place. This function doesn't guarantee cache
@@ -73,12 +72,10 @@ namespace Svelto.ECS
         /// <param name="action"></param>
         /// <typeparam name="T"></typeparam>
         /// <typeparam name="T1"></typeparam>
-        void ExecuteOnEntities<T, T1>(int groupID, ActionRef<T, T1> action) where T : IEntityStruct where T1 : IEntityStruct;
-        void ExecuteOnEntities<T, T1>(ActionRef<T, T1> action) where T : IEntityStruct where T1 : IEntityStruct;
-        
-        void ExecuteOnEntities<T, T1, W>(int groupID, ref W value, ActionRef<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct;
-        void ExecuteOnEntities<T, T1, W>(ref W value, ActionRef<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct;
-        void ExecuteOnEntities<T, T1, W>(W value, ActionRef<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct;
+        void ExecuteOnEntities<T, T1>(int groupID, EntitiesAction<T, T1> action) where T : IEntityStruct where T1 : IEntityStruct;
+        void ExecuteOnEntities<T, T1>(EntitiesAction<T, T1> action) where T : IEntityStruct where T1 : IEntityStruct;
+        void ExecuteOnEntities<T, T1, W>(int groupID, ref W value, EntitiesAction<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct;
+        void ExecuteOnEntities<T, T1, W>(ref W value, EntitiesAction<T, T1, W> action) where T : IEntityStruct where T1 : IEntityStruct;
         /// <summary>
         /// Execute an action on ALL the entities regardless the group. This function doesn't guarantee cache
         /// friendliness even if just EntityStructs are used. 
@@ -86,8 +83,8 @@ namespace Svelto.ECS
         /// </summary>
         /// <param name="action"></param>
         /// <typeparam name="T"></typeparam>
-        void ExecuteOnAllEntities<T>(ActionRef<T> action) where T : IEntityStruct;
-        void ExecuteOnAllEntities<T, W>(ref W  value, ActionRef<T, W> action) where T : IEntityStruct;
+        void ExecuteOnAllEntities<T>(EntityAction<T> action) where T : IEntityStruct;
+        void ExecuteOnAllEntities<T, W>(ref W  value, EntityAction<T, W> action) where T : IEntityStruct;
         /// <summary>
         /// ECS is meant to work on a set of Entities. Working on a single entity is sometime necessary, but using
         /// the following functions inside a loop would be a mistake as performance can be significantly impacted
@@ -108,16 +105,22 @@ namespace Svelto.ECS
         /// <param name="egid"></param>
         /// <param name="action"></param>
         /// <typeparam name="T"></typeparam>
-        void ExecuteOnEntity<T>(EGID egid, ActionRef<T> action) where T : IEntityStruct;
-        void ExecuteOnEntity<T>(int     id,   ActionRef<T> action) where T : IEntityStruct;
-        void ExecuteOnEntity<T>(int     id,   int          groupid, ActionRef<T>    action) where T : IEntityStruct;
-        void ExecuteOnEntity<T, W>(EGID egid, ref W        value,   ActionRef<T, W> action) where T : IEntityStruct;
-        void ExecuteOnEntity<T, W>(int  id,   ref W        value,   ActionRef<T, W> action) where T : IEntityStruct;
-        void ExecuteOnEntity<T, W>(int  id,   int          groupid, ref W           value, ActionRef<T, W> action) where T : IEntityStruct;
+        void ExecuteOnEntity<T>(EGID egid, EntityAction<T> action) where T : IEntityStruct;
+        void ExecuteOnEntity<T>(int     id,   EntityAction<T> action) where T : IEntityStruct;
+        void ExecuteOnEntity<T>(int     id,   int          groupid, EntityAction<T>    action) where T : IEntityStruct;
+        void ExecuteOnEntity<T, W>(EGID egid, ref W        value,   EntityAction<T, W> action) where T : IEntityStruct;
+        void ExecuteOnEntity<T, W>(int  id,   ref W        value,   EntityAction<T, W> action) where T : IEntityStruct;
+        void ExecuteOnEntity<T, W>(int  id,   int          groupid, ref W           value, EntityAction<T, W> action) where T : IEntityStruct;
 
         bool Exists<T>(EGID egid) where T : IEntityStruct;
         
         bool HasAny<T>() where T:IEntityStruct;
         bool HasAny<T>(int group) where T:IEntityStruct;
     }
+
+    public delegate void EntityAction<T, W>(ref T target, ref W value);
+    public delegate void EntityAction<T>(ref T target);
+    public delegate void EntitiesAction<T, T1, W>(ref T target, ref T1 target1, ref W value, int index);
+    public delegate void EntitiesAction<T, W>(ref T target, ref W value, int index);
+    public delegate void EntitiesAction<T>(ref T target, int index);
 }
\ No newline at end of file