References as members

• Classes can have references as members.

• Reference replaces pointer and adds design constraints we may need.

• Reference member must be initialized early.

• In fact, before constructor body is entered!

• New syntax for constructors: the initializer list. Consider:

      class Point
      {
      private:
          Graph& m_g;
          int    m_x;
          int    m_y;
      public:
          Point( Graph& g, int x, int y );
      };