Associative Chains in C++

Listing 1

class Reservation
{
public:
  int resource_type;
  int resource_id;
  int user_id;
  time_t range[2];
};
 ...
int Reservation::*t = &Reservation::resource_type;
Reservation r;
int resource_type = r.*t;

class User
{
public:
  std::string name;  
};
class Reservation_Hack
{
public:
  int resource_type;
  int resource_id;
  User user;
  time_t range[2];
};