anchor.diff:      (setf (class-direct-slots class) ())
       (setf (class-direct-default-initargs class) ())
       (setf (class-precedence-list class) (list class))
  +    (setf (class-slot-cache class) (make-array 0))
       (setf (class-slots class) ())
       class))
   ;; (It's now okay to define subclasses of t.)
  
positive.code: (defun (setf slot-contents) (new-value slots location)
    (setf (svref slots location) new-value))
  
  (defun std-slot-value (instance slot-name)
    (let* ((location (slot-location (class-of instance) slot-name))
           (slots (std-instance-slots instance))
           (val (slot-contents slots location)))
      (if (eq secret-unbound-value val)
          (error "The slot ~S is unbound in the object ~S."
                 slot-name instance)
          val)))
  (defun slot-value (object slot-name)
    (if (eq (class-of (class-of object)) the-class-standard-class)
        (std-slot-value object slot-name)
  
negative.code: 
  (defvar the-slots-of-standard-class) ;standard-class's class-slots
  (defvar the-class-standard-class)    ;standard-class's class metaobject
  (defvar *standard-class-effective-slots-position*) ; Position of the effective-slots slot in standard-class.
  (defvar *standard-class-slot-cache-position*)
  
  (defun slot-location (class slot-name)
    (if (and (eq slot-name 'effective-slots)
             (eq class the-class-standard-class))
        *standard-class-effective-slots-position*
        (let ((slot (find slot-name
                          (class-slots class)
                          :key #'slot-definition-name)))
  