(defmacro with-cvlab-foreign-pointers ((pointers-var npointers-var cvlab-objects-form)
                                       &body forms)
  (let ((cvlab-objects (gensym "CVLAB-OBJECTS"))
        (i (gensym "I"))
        (object (gensym "OBJECT")))
    `(let* ((,cvlab-objects ,cvlab-objects-form)
            (,npointers-var (length ,cvlab-objects))
            (,i 0))
       (with-foreign-objects ((,pointers-var :pointer ,npointers-var))
         (map nil (lambda (,object)
                    (setf (mem-aref ,pointers-var :pointer ,i)
                          (slot-value ,object 'pointer))
                    (incf ,i))
              ,cvlab-objects)
         ,@forms))))