anchor.diff:  ;; TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   ;; SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   
  -;; $Id: virtual-slots.lisp,v 1.4 2006-09-05 13:16:18 espen Exp $
  +;; $Id: virtual-slots.lisp,v 1.5 2006-09-13 10:52:16 espen Exp $
   
   (in-package "GFFI")
   
  
positive.code:     #'(lambda (object) (declare (ignore object)) nil))
  
     ;; An explicit boundp function has been supplied
     ((slot-boundp slotd 'boundp) (slot-value slotd 'boundp))
     
     ;; An unbound value has been supplied
     ((slot-boundp slotd 'unbound)
      (let ((reader-function (compute-slot-reader-function slotd nil))
  
negative.code: 
  (defmethod compute-slot-reader-function ((slotd effective-virtual-slot-definition) &optional signal-unbound-p)
    (declare (ignore signal-unbound-p))
    (let ((getter (slot-value slotd 'getter)))
      #-sbcl getter
      #+sbcl
      (etypecase getter
        (symbol #'(lambda (object) (funcall getter object)))
        (function getter))))
  
  (defmethod compute-slot-boundp-function ((slotd effective-virtual-slot-definition))
    (cond
  