GBBOPEN-USER> (define-unit-class bunny ()
                (x y))
#<STANDARD-UNIT-CLASS GBBOPEN-USER::BUNNY>
GBBOPEN-USER> (defvar *bunny-class* *)
*BUNNY-CLASS*
GBBOPEN-USER> (ensure-finalized-class *bunny-class*)
#<STANDARD-UNIT-CLASS GBBOPEN-USER::BUNNY>
GBBOPEN-USER> (defvar *slot1* (car (last (class-slots *bunny-class*))))
*SLOT1*
GBBOPEN-USER> (define-ks bunny-alert-ks
                :rating 100
                :trigger-events ((nonlink-slot-updated-event bunny))
                :execution-function 'bunny-alert-ks-function)
#<KS BUNNY-ALERT-KS>
GBBOPEN-USER> (eq *slot1*
                  (car (last (class-slots *bunny-class*))))
NIL
GBBOPEN-USER> (car (last (class-slots *bunny-class*)))
#<Nonlink-slot Y>
GBBOPEN-USER> (defun bunny-alert-ks-function (ksa)
                (let ((bunny (sole-trigger-instance-of ksa)))
                  (when (and (slot-boundp bunny 'y)
                             (> (y-of bunny) 10))
                    (format t "Bunny ~S went too high~%" bunny))))
BUNNY-ALERT-KS-FUNCTION
GBBOPEN-USER> (spawn-control-shell-thread)
#<SB-THREAD:THREAD "Agenda Shell" RUNNING {10141523A3}>
;; Control shell 1 started
GBBOPEN-USER> (make-instance 'bunny :x 5 :y 8)
#<BUNNY 1>
GBBOPEN-USER> (incf (y-of (find-instance-by-name 1 'bunny)))
9
GBBOPEN-USER> (incf (y-of (find-instance-by-name 1 'bunny)))
10
GBBOPEN-USER> (incf (y-of (find-instance-by-name 1 'bunny)))
11
Bunny #<BUNNY 1> went too high
GBBOPEN-USER>