(goops.info.gz) Default Class Redefinition Behaviour

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(goops.info.gz) Redefining a Class

(goops.info.gz) Customizing Class Redefinition

 
 Default Class Redefinition Behaviour
 ------------------------------------
 
 GOOPS' default answer to this question is as follows.
 
    * All existing direct instances of `<my-class>' are converted to be
      instances of the new class.  This is achieved by preserving the
      values of slots that exist in both the old and new definitions,
      and initializing the values of new slots in the usual way (
      make Basic Instance Creation.).
 
    * All existing subclasses of `<my-class>' are redefined, as though
      the `define-class' expressions that defined them were re-evaluated
      following the redefinition of `<my-class>', and the class
      redefinition process described here is applied recursively to the
      redefined subclasses.
 
    * Once all of its instances and subclasses have been updated, the
      class metaobject previously bound to the variable `<my-class>' is
      no longer needed and so can be allowed to be garbage collected.
 
 To keep things tidy, GOOPS also needs to do a little housekeeping on
 methods that are associated with the redefined class.
 
    * Slot accessor methods for slots in the old definition should be
      removed from their generic functions.  They will be replaced by
      accessor methods for the slots of the new class definition.
 
    * Any generic function method that uses the old `<my-class>'
      metaobject as one of its formal parameter specializers must be
      updated to refer to the new `<my-class>' metaobject.  (Whenever a
      new generic function method is defined, `define-method' adds the
      method to a list stored in the class metaobject for each class
      used as a formal parameter specializer, so it is easy to identify
      all the methods that must be updated when a class is redefined.)
 
 If this class redefinition strategy strikes you as rather
 counter-intuitive, bear in mind that it is derived from similar
 behaviour in other object systems such as CLOS, and that experience in
 those systems has shown it to be very useful in practice.
 
 Also bear in mind that, like most of GOOPS' default behaviour, it can
 be customized...
 

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(goops.info.gz) Redefining a Class

(goops.info.gz) Customizing Class Redefinition