added defined to CompileOptional

include/CompileOptional.h

@@ -5,17 +5,27 @@
 #ifndef CONST_CONTAINER_COMPILEOPTIONAL_H_
 #define CONST_CONTAINER_COMPILEOPTIONAL_H_
 
+#include <type_traits>
+
 namespace cc {
-	template<typename, bool = false>
+	template<typename, bool Cond = false>
 	class CompileOptional {};
+	
+	template<typename T>
+	class CompileOptional<T, false> {
+		public:
+			using defined = std::false_type;
+	};
 
 	template<typename T>
 	class CompileOptional<T, true> {
+		public:
+			using defined = std::true_type;
+			operator T&() { return _data; }
 		private:
 			T _data;
-		public:
-			operator T&() { return _data; }
 	};
+	
 }
 
-#endif //UDIFF_COMPILEOPTIONAL_H_
+#endif //CONST_CONTAINER_COMPILEOPTIONAL_H_