259: Sidetrip

Smalltalk links together the metaclasses in a class hierarchy. Those links form a metaclass hierarchy that parallels that of the corresponding classes. The metaclass hierarchy terminates in a class named Class, which is a subclass of the Behavior class:

                                  *-------------------------------* 
                                  | Behavior class                | 
                                  *-------------------------------* 
                                    | 
                                    | subclass 
                                    v 
                                  *-------------------------------* 
                                  | Class class                   | 
                                  *-------------------------------* 
                                    | 
                                    | subclass 
                                    v 
*--------------*     instance     *-------------------------------* 
| Object class | <--------------- | Object class's metaclass      | 
*--------------*                  *-------------------------------* 
  |                                 | 
  | subclass                        | subclass 
  v                                 v 
*--------------*     instance     *-------------------------------* 
| Food class   | <--------------- | Food class's metaclass        | 
*--------------*                  *-------------------------------* 
  |                                 | 
  | subclass                        | subclass 
  v                                 v 
*-------------------*   instance  *-------------------------------* 
| Vegetable class   | <---------- | Vegetable class's metaclass   | 
*-------------------*             *-------------------------------*