问内存问题

EN

class InputSystem : boost::serialization::singleton<InputSystem>
{
private:
   boost::shared_ptr<sf::Window> mInputWindow;
public:
   InputSystem()
   {
      mInputWindow = boost::shared_ptr<sf::Window>( new sf::Window(someARgs) );
      someMethod();
   }

   void someMethod()
   {
      mInputWindow->...() // Calling some methods of sf::Window class
      // Everything  is fine here
   }

   const sf::Input &Handle() const
   {
      return mInputWindow.get()->GetInput();
   }
};

void main()
{
   InputSystem::get_mutable_instance().Handle(); // Here is all members of InputSystem have invalid addresses in memory (0x000)
}