good_enough.c++

bool present;
		struct storage_t {
			T& ref;
		} storage;

		template <typename... Tn>
		void place( Tn&&... argn ) {
			assert( !present );
			unchecked_place( std::forward<Tn>( argn )... );
		}

		template <typename... Tn>
		void unchecked_place( Tn&&... argn ) {
			new ( std::addressof( storage ) ) storage_t( std::forward<Tn>( argn )... );
			present = true;
		}

		void destroy( ) {
			assert( present );
			unchecked_destroy( );
		}

		void unchecked_destroy( ) {
			storage.~storage_t( );
			present = false;
		}