// MT2Q4.cpp

#include <iostream>
#include <vector>

struct ICommand
{
  virtual void execute() = 0;
};

class invoker
{
public:
  void invoke()
  {
    for(size_t i=0; i<commands.size(); ++i)
      commands[i]->execute();
  }
  static void Register(ICommand* pCommand)
  {
    commands.push_back(pCommand);
  }
private:
  static std::vector<ICommand*> commands;
};

std::vector<ICommand*> invoker::commands;

void scope1()
{
  static bool eventHappened = false;
  static bool firstPass = true;
  class comm1 : public ICommand
  {
    void execute() { eventHappened = true; }
  };
  if(firstPass)
  {
    firstPass = false;
    invoker inv1;
    inv1.Register(new comm1);
  }
  if(eventHappened)
    std::cout << "\n  event recorded in scope1";
  else
    std::cout << "\n  no event yet in scope1";
}

void scope2()
{
  static bool eventHappened = false;
  static bool firstPass = true;
  class comm2 : public ICommand
  {
    void execute() { eventHappened = true; }
  };
  if(firstPass)
  {
    firstPass = false;
    invoker inv2;
    inv2.Register(new comm2);
  }
  if(eventHappened)
    std::cout << "\n  event recorded in scope2";
  else
    std::cout << "\n  no event yet in scope2";
}

void main()
{
  invoker inv;
  for(int i=0; i<6; ++i)
  {
    if(i==3)
      inv.invoke(); // event happened
    scope1();
    scope2();
  }
}