Utility: fix function classes to have a common interface for virtual dispatch

Utility/Inc/utility_function.hpp

@@ -11,11 +11,26 @@
 namespace Utility
 {
 
+template<class>
+class IFunction;
+
+template<typename R, typename... Args>
+class IFunction<R(Args...)>
+{
+public:
+  using result_type = R;
+
+  virtual ~IFunction()
+  {}
+
+  virtual result_type operator()(Args... args) = 0;
+};
+
 template<class>
 class Function;
 
 template<typename R, typename... Args>
-class Function<R(Args...)>
+class Function<R(Args...)> : public IFunction<R(Args...)>
 {
 public:
   using result_type = R;
@@ -29,9 +44,13 @@ public:
     assert(callable_);
   }
 
-  result_type operator()(Args&&... args)
+  ~Function() override
   {
-    return (*callable_)(std::forward<Args>(args)...);
+  }
+
+  result_type operator()(Args... args) override
+  {
+    return (*callable_)(args...);
   }
 
 private:
@@ -42,7 +61,7 @@ template<class, class>
 class FunctionOwned;
 
 template<typename H, typename R, typename... Args>
-class FunctionOwned<H, R(Args...)>
+class FunctionOwned<H, R(Args...)> : public IFunction<R(Args...)>
 {
 public:
   using source = H;
@@ -57,9 +76,12 @@ public:
     assert(callable_);
   }
 
-  result_type operator()(Args&&... args)
+  ~FunctionOwned() override
+  {}
+
+  result_type operator()(Args... args) override
   {
-    return (src_->*callable_)(std::forward<Args>(args)...);
+    return (src_->*callable_)(args...);
   }
 
 private: