incomplete-instance-p

Purpose
Determine if a unit instance is incomplete.

Package   :gbbopen

Module   :gbbopen-core

Arguments and values

Returns
True if the unit instance is incomplete; nil otherwise.

See also
    instance-deleted-p

Example
Define an event function that recomputes the area of a complete unit instance when the value of its height or width slot changes:

  (defun update-area-evfn (event-name 
                             &key instance
                             &allow-other-keys)
    (declare (ignore event-name))
    ;; Do not compute the area of an incomplete instance:
    (unless (incomplete-instance instance)
      (setf (area-of instance) 
            (* (width-of instance) (height-of instance)))))

  (add-event-function 'update-area-evfn 
                      'rectangle
                      :slot-names '(width height))

incomplete-instance-p