Menu Stack

pushpop.cpp

#include <stack>
#include <memory>
#include <cassert>
 
// Polymorphic base class for menus
class Menu
{
public:
  // Common to all menus:
  // (for example)
  virtual void draw() = 0;
  virtual void onMouseMove(int x, int y) = 0;
  virtual void onMouseButton(int button, bool is_down) = 0;
  // ... etc.
}
 
// A concrete menu class representing the main menu:
class MainMenu : public Menu
{
public:
  MainMenu() {}
    
  virtual void draw() { /* ... */ }
  virtual void onMouseMove(int x, int y){ /* ... */ }
  virtual void onMouseButton(int button, bool is_down) { /* ... */ }
  // ...
}
 
// Of couse, normally you will have other menus as well.
 
 
int main(int argc, char** argv)
{
  // std::stack is an adapter container that uses std::deque by default.
  // You could just as easily use std::deque, std::vector, or std::list directly
  // if you change push() to push_back(), top() to back(), and pop() to pop_back().
  std::stack<std::unique_ptr<Menu>> menus;
  
  Menu* m = new MainMenu();
 
  menus.push(std::unique_ptr<Menu>(m));
  
  assert(menus.top().get() == m);
  
  menus.pop();  // the object pointed to by `m` is destroyed when the std::unique_ptr in the stack is removed.
}