#include <boost/signals2.hpp>
#include <boost/make_shared.hpp>
#include <boost/shared_ptr.hpp>
#include <iostream>

struct A
{ boost::signals2::signal<void()> Signal; };

struct B
{ boost::signals2::signal<void()> Signal; };

int main()
{
  boost::shared_ptr<A> pA = boost::make_shared<A>();
  boost::shared_ptr<B> pB = boost::make_shared<B>();

  std::cout << "Should be 0: " << pA->Signal.num_slots() << std::endl;

  pA->Signal.connect(pB->Signal);

  std::cout << "Should be 1: " << pA->Signal.num_slots() << std::endl;

  pA->Signal();

  pB.reset();

  std::cout << "Ideally 0, but I think it will be 1 which would mean we are about to get some undefined behavior: " << pA->Signal.num_slots() << std::endl;

  pA->Signal();

  return 0;
}