improve plugin facing api with c++ helpers

solanaceae/plugin/plugin_manager.hpp

@@ -21,29 +21,7 @@ void g_provideInstance__internal(const char* id, const char* version, const char
 
 } // extern C
 
-namespace internal {
-	template<typename T>
-	class g_type_version {
-		typedef char yes[1];
-		typedef char no [2];
-
-		template<typename C> static yes& test_version(decltype(&C::version));
-		template<typename C> static no& test_version(...);
-
-		static bool const has_version = sizeof(test_version<T>(nullptr)) == sizeof(yes);
-		static constexpr const char* get_version(void) {
-			if constexpr (has_version) {
-				return T::version;
-			} else {
-				return "UNK"; // default version
-			}
-		}
-
-		public:
-			static constexpr const char* version = get_version();
-	};
-} // internal
-
+#include "./version_helper.inl"
 
 // templated helper, use or make sure vtable is right
 template<typename T>