diff --git a/source/ecs/manager.d b/source/ecs/manager.d
index 5719f6e..496b6ef 100644
--- a/source/ecs/manager.d
+++ b/source/ecs/manager.d
@@ -312,7 +312,7 @@ class EntityManager
             }
         }
 
-        static string genCompList()()
+        /*static string genCompList()()
         {
 
             static foreach (member; __traits(allMembers, Sys.EntitiesData))
@@ -512,6 +512,195 @@ class EntityManager
                 }
             }
             return ret;
+        }*/
+
+        static struct ComponentsIndices
+        {
+            string[] readonly;
+            string[] excluded;
+            string[] optional;
+            string[] mutable;
+            string[] req;
+
+        }
+
+        static void allocateSystemComponents(ComponentsIndices componentsInfo)(ref System system)
+        {
+            size_t req = componentsInfo.req.length;
+            size_t opt = componentsInfo.optional.length;
+            size_t excluded = componentsInfo.excluded.length;
+            size_t read_only = componentsInfo.readonly.length;
+            size_t modified = componentsInfo.mutable.length;
+
+            if (req > 0)
+                system.m_components = Mallocator.instance.makeArray!ushort(req);
+            if (opt > 0)
+                system.m_optional_components = Mallocator.instance.makeArray!ushort(opt);
+            if (excluded > 0)
+                system.m_excluded_components = Mallocator.instance.makeArray!ushort(excluded);
+            if (read_only > 0)
+                system.m_read_only_components = Mallocator.instance.makeArray!ushort(read_only);
+            if (modified > 0)
+                system.m_modified_components = Mallocator.instance.makeArray!ushort(modified);
+
+        }
+
+        bool checkExcludedComponentsSomething(Sys)()
+        {
+            return __traits(compiles, allSameType!(string, typeof(Sys.ExcludedComponents))) && allSameType!(string,
+                    typeof(Sys.ExcludedComponents)) && isExpressions!(Sys.ExcludedComponents);
+        }
+
+        static ComponentsIndices getComponentsInfo()
+        {
+            ComponentsIndices componentsInfo;
+
+            foreach (member; __traits(allMembers, Sys.EntitiesData))
+            {
+                alias MemberType = typeof(__traits(getMember, Sys.EntitiesData, member));
+                if (member == "length" || is(MemberType == Entity[]) || is(MemberType == const(Entity)[]))
+                {
+                    continue;
+                }
+                string name;
+                static if (isArray!MemberType)
+                { // Workaround. This code is never called with: not an array type, but compiler prints an error
+                    name = Unqual!(ForeachType!MemberType).stringof;
+                }
+
+                bool isOptional;
+                bool isExcluded;
+                bool isReadOnly;
+
+                // isMutable!( ForeachType!(MemberType) );
+                if (is(CopyConstness!(ForeachType!(MemberType), int) == const(int)))
+                {
+                    isReadOnly = true;
+                }
+
+                foreach (att; __traits(getAttributes, __traits(getMember, Sys.EntitiesData, member)))
+                {
+                    if (att == "optional")
+                    {
+                        isOptional = true;
+                    }
+                    else if (att == "excluded")
+                    {
+                        isExcluded = true;
+                    }
+                    if (att == "readonly")
+                    {
+                        isReadOnly = true;
+                    }
+                }
+                if (isReadOnly)
+                {
+                    componentsInfo.readonly ~= name;
+                }
+                else
+                {
+                    componentsInfo.mutable ~= name;
+                }
+                if (isExcluded)
+                {
+                    componentsInfo.excluded ~= name;
+                }
+                if (isOptional)
+                {
+                    componentsInfo.optional ~= name;
+                }
+                if (isReadOnly)
+                {
+                    componentsInfo.readonly ~= name;
+                }
+                if (isExcluded == false && isOptional == false)
+                { //is Req
+                    componentsInfo.req ~= name;
+                }
+
+                assert(!(isOptional && isExcluded),
+                        "EntitiesData member can't have both \"@optional\" and \"@excluded\".");
+
+            }
+
+            static if (__traits(hasMember, Sys, "ExcludedComponents"))
+            {
+                static if (is(Sys.ExcludedComponents == enum))
+                {
+                    foreach (str; Fields!(Sys.ExcludedComponents))
+                    {
+                        ComponentInfo info;
+                        info.isExcluded = true;
+                        info.name = str.stringof;
+                    }
+                }
+                else static if (checkExcludedComponentsSomething!Sys)
+                {
+                    foreach (str; Sys.ExcludedComponents)
+                    {
+                        ComponentInfo info;
+                        info.isExcluded = true;
+                        info.name = str;
+
+                    }
+
+                }
+            }
+            return componentsInfo;
+        }
+
+        static void genCompList()(ref System system, ref HashMap!(const(char)[], ushort) components_map)
+        {
+
+            foreach (member; __traits(allMembers, Sys.EntitiesData))
+            {
+                alias MemberType=typeof(__traits(getMember, Sys.EntitiesData, member));
+
+                static if (isFunction!(__traits(getMember, Sys.EntitiesData, member)))
+                    static assert(0, "EntitiesData can't have any function!");
+                else static if (member == "length")
+                {
+                    static assert(isIntegral!(MemberType), "EntitiesData 'length' member must be integral type.");
+                    static assert(MemberType.sizeof > 1, "EntitiesData 'length' member can't be byte or ubyte.");
+                }
+                else static if (!(isArray!(MemberType)))
+                    static assert(0, "EntitiesData members should be arrays of elements!");
+            }
+
+            enum ComponentsIndices componentsInfo = getComponentsInfo();
+            allocateSystemComponents!(componentsInfo)(system);
+
+            foreach (iii, name; componentsInfo.req)
+            {
+                ushort comp = components_map.get(cast(char[]) name, ushort.max);
+                assert(comp != ushort.max, "Can not register system: component not present");
+                system.m_components[iii] = comp;
+            }
+            foreach (iii, name; componentsInfo.excluded)
+            {
+                ushort comp = components_map.get(cast(char[]) name, ushort.max);
+                assert(comp != ushort.max, "Can not register system: component not present");
+                system.m_excluded_components[iii] = comp;
+            }
+            foreach (iii, name; componentsInfo.optional)
+            {
+                ushort comp = components_map.get(cast(char[]) name, ushort.max);
+                assert(comp != ushort.max, "Can not register system: component not present");
+                system.m_optional_components[iii] = comp;
+            }
+            foreach (iii, name; componentsInfo.readonly)
+            {
+                ushort comp = components_map.get(cast(char[]) name, ushort.max);
+                assert(comp != ushort.max, "Can not register system: component not present");
+                system.m_read_only_components[iii] = comp;
+            }
+            foreach (iii, name; componentsInfo.mutable)
+            {
+                ushort comp = components_map.get(cast(char[]) name, ushort.max);
+                assert(comp != ushort.max, "Can not register system: component not present");
+                system.m_modified_components[iii] = comp;
+            }
+
         }
 
         static string genFillInputData()()
@@ -709,7 +898,8 @@ class EntityManager
         (cast(Sys*) system.m_system_pointer).__ecsInitialize();
         system.jobs = (cast(Sys*) system.m_system_pointer)._ecs_jobs;
 
-        mixin(genCompList());
+        //mixin(genCompList());
+        genCompList(system, components_map);
 
         ushort sys_id = systems_map.get(Sys.stringof, ushort.max);
         if (sys_id < systems.length)