3.cpp

class replacement
{
public:
  void setter(int a)
  {
    _setter(this, a);
  }

  int getter() const
  {
    return _getter(this);
  }

  virtual ~replacement() = 0;
  virtual int virtual_getter() const = 0;

  static setter_fn_t *_setter;
  static getter_fn_t *_getter;
};