removed metadata base class. removed nodata dependency to metadata (added by accident)

source/RobotAPI/libraries/armem/core/base/EntityInstanceBase.h

@@ -9,25 +9,13 @@
 namespace armarx::armem::base
 {
 
-    struct Metadata
-    {
-        virtual ~Metadata() = default;
-
-        /// TODO @peller
-        virtual void access() const = 0;
-    };
-
     /**
      * @brief Default data of an entity instance (empty).
      */
-    struct NoData : public Metadata
+    struct NoData
     {
         virtual ~NoData() = default;
 
-        void access() const final
-        {
-        }
-
         bool operator==(const NoData& other)
         {
             return true;
@@ -42,9 +30,11 @@ namespace armarx::armem::base
     /**
      * @brief Metadata of an entity instance.
      */
-    struct EntityInstanceMetadata : public Metadata
+    struct EntityInstanceMetadata
     {
-        ///
+
+        virtual ~EntityInstanceMetadata() = default;
+
         /**
          * @brief Time this instance refers to.
          *
@@ -68,9 +58,8 @@ namespace armarx::armem::base
         /// A counter how often the instance has been accessed.
         mutable unsigned long numAccessed = 0;
 
-        virtual ~EntityInstanceMetadata() = default;
-
-        void access() const final;
+        /// Called whenever the entity instance this metadata belongs to is accessed (e.g. queried).
+        void access() const;
 
         bool operator==(const EntityInstanceMetadata& other) const;
         inline bool operator!=(const EntityInstanceMetadata& other) const