stopwatch iodiom high precision timer for measuring software performance

stopwatch.h

    /**
     * @brief stopwatch idiom high precision timer for measuring software performance
     * @tparam PolicyClock - std::chrono::steady_clock (default), system_clock, high_resolution_clock
     */
    template<typename PolicyClock = std::chrono::steady_clock>
        class stopwatch {

        using clock_t = PolicyClock;

        public:

            using time_point_t = typename clock_t::time_point;

            stopwatch() = default;

            time_point_t static now() {
                return clock_t::now();
            }

            time_point_t start() {
                before = clock_t::now();
                return before;
            }

            time_point_t stop() {
                after = clock_t::now();
                return after;
            }

            template<typename duration_t>
            uint64_t count() {
                return std::chrono::duration_cast<duration_t>(after - before).count();
            }

            float seconds() {
                std::chrono::duration<float> t = after - before;
                return t.count();
            }

        private:

            time_point_t before;
            time_point_t after;

    };