Function: MAYBE-ADD-PERSISTENT-OBJECT-CLASS

Source

(defun maybe-add-persistent-object-class (class direct-superclasses)
  ;; Add PERSISTENT-OBJECT to the superclass list if necessary.
  (let ((root-class (find-class 'persistent-object nil))
        (persistent-class (find-class 'persistent-class)))
    (if (or (null root-class)
            (eql class root-class)
            (find-if (lambda (direct-superclass)
                       (member persistent-class
                               (compute-class-precedence-list
                                (class-of direct-superclass))))
                     direct-superclasses))
        direct-superclasses
      (cons root-class direct-superclasses))))