Question

I’m implementing a Timer such that the time spent on different kinds of events are categorized and listed. The class declaration goes something as follows:

#include "timer_event.h"
#include <boost/timer.hpp>
#include <vector>

class Timer {
 private:
  class TimedEvent;
 public:
  static TimedEvent* Time(TimerEvent e);
 protected:
 private:
  class TimedEvent {
       public:
    TimedEvent(double seconds, TimerEvent event);
    ~TimedEvent();
   protected:
   private:
    TimerEvent event_;
    double seconds_;
  };
  static boost::timer watch_;
};

Then, in the source file, I’m planning to implement the “Time” function as something like:

TimedEvent* Time(TimerEvent e) {
  TimedEvent* ret = new TimedEvent(watch_.elapsed(),e);
  return ret;
}

However, the compiler’s error message is:

../utils/timer.cc:24:1: error: ‘TimedEvent’ does not name a type

Could anyone try to help?

---

–Revised:

I’ve modified the Time function so that it now looks like:

Timer::TimedEvent* Timer::Time(TimerEvent e) {
  TimedEvent* ret = new TimedEvent(watch_.elapsed(),e);
  return ret;
}

However, since “Time” is declared as a static function in the class declaration. We need to declare the static objects in the cpp file since I’m getting this in the linker’s error message:

timer.cc:(.text+0x76): undefined reference to `Timer::TimedEvent::TimedEvent(double, TimerEvent)'

What kind of static object should I declare in the source file then?

Answer 1

That’s a compiler error, not a linker error.

Presumably your Time was supposed to look like this:

TimedEvent* Timer::Time(TimerEvent e) {
   TimedEvent* ret = new TimedEvent(watch_.elapsed(),e);
   return ret;
}

I really dislike how everything starts with “Time”, by the way!

Now, inside the function you can probably use TimedEvent as it is. But the return type isn’t inside the function: you’ll have to qualify the type as Timer::TimedEvent for that:

Timer::TimedEvent* Timer::Time(TimerEvent e) {
   TimedEvent* ret = new TimedEvent(watch_.elapsed(),e);
   return ret;
}

In addition, you need to define Timer::TimedEvent‘s constructor somewhere.