anchor.diff:                                                   direct-superclasses
                                                    :test #'eq)))
                           (setq initargs-updated t))))))
  -        ;; NB: This does not ever check the value of SLOTS.
  -        ;;;
  -        ;; Such a check would have to be performed in a completely
  -        ;; implementation-specific regard, in order to detect what the
  -        ;; assumed DIRECT-SUPERCLASES slot would be named, for any
  -        ;; instance in which SLOTS would be TYPEP CONS.
  -        ;;
  -        ;; This could also, then, dispatch in a portable way singularly
  -        ;; for the case of (EQ SLOTS T)
  -        ;;
  -        ;; In lieu of that, this will modify SLOTS in many
  -        ;; instances. The modification might subsequently be ignored by
  -        ;; the next method.
  -        ;;
  -        ;; This method, as such, might be left undefined in the top level of
  -        ;; the containing source file.
  +
           (setq direct-superclasses (ensure-tgt-superclass))
   
  -        ;; NB: Not useful if the updated value is being ignored
  -        ;;     by the implementation
  +        ;; NB: Not useful, if the updated value is being ignored
  +        ;;     by the implementation. See also SHARED-INITIALIZE
   
           (dispatch)))))
   
  
positive.code:                                 &rest initargs &key
                                                   direct-superclasses
                                                   &allow-other-keys)
    ;; ensure that any call to MAKE-INSTANCE of a SINGLETON will produce
    ;; an object that is a subtype of the original SINGLETON
  
    ;; NB: In some call sequences -- such as when a singleton is
    ;; created initially from DEFCLASS, rather than CHANGE-CLASS from a
    ;; FORWARD-RERFERENCED-CLASS -- this may be "Early enough" to catch
    ;; where PCL is initially setting the direct-superclasses list for the
    ;; class definition.
    ;;
    ;; NB: See also CHANGE-CLASS, SHARED-INITIALIZE
  
    (let ((tgt-class (find-class 'singleton))
          (unused-class (find-class 'standard-object))
  
negative.code: 
  ;; --
  
  ;; FIXME: Test DEFSINGLETON with a superclass not being of a metatype
  ;; SINGLETON, but such that a direct superclass of that class is of
  ;; metatype SINGLETON
  
  (eval-when ()
  
  