#include <boost/bind.hpp>
#include <boost/thread_safe_signal.hpp>
#include <iostream>

void myfunction(int arg)
{
  std::cout << "arg is " << arg << std::endl;
};

struct coordinate
{
  int x;
  int y;
};

int main()
{
  boost::signal<void ()> sig;
  boost::shared_ptr<coordinate> coord(new coordinate);
  coord->x = 5;
  sig.connect(boost::bind(&myfunction, boost::signalslib::track(coord, boost::ref(coord->x))));
  sig();
  coord->x = 4;
  sig();
  return 0;
}