(defclass RBR-object ()
  ((name :accessor name :initform 'unknown :initarg :name )
   (TT-slot :accessor TT-slot :initform 'unknown :initarg :TT-slot))
  )

;; function to make instances of defined classes
;;      this can used directly on the RHS of rules as
;;      well as at top level to construct the instances of an object base
;;   first tests that intended instance is a sub of RBR-object
;;   increments global time tag


(defun make-RBR-instance (&rest args)
     "takes all args passed to make-RBR-instance and passes them to make-instance"
   (if (not (typep (first args) RBR-object)) (and (print  'error)nil  )
     (let ((args-w-tag (append args (list ':TT-slot *tag*))))
       (push
         (apply #'make-instance args-w-tag) *OB* )
       (setf *tag* (+ *tag* 1)))))


;; the following illustrates the creation of a single RBR instance by
;;      the use of make-RBR-instance
;
;(make-RBR-instance 'train
;        :place 4
;        :in-motion 'yes
;        :name 1 )               ;note slot and accessor inherited from RBR-object