text: #ifndef _ROS_TIMER_HPP
  #define _ROS_TIMER_HPP
  
  #include "Timer.hpp"
  #include <ros/ros.h>
  
  class ROSTimer : public Timer
  {
  private:
     ros::Timer      _timer;
     ros::NodeHandle _nh;
  
     bool   _oneshot;
     double _interval;
     bool   _expired;
  
     void TimerCallback(const ros::TimerEvent& event);
  public:
     ROSTimer();
     ~ROSTimer() {}
     
     void SetInterval(double t) override;
     void StartOnce() override;
     void Stop() override;
     bool Expired() const override;
  };
  
  #endif // _ROS_TIMER_HPP