🚀 go-pugleaf

CLtL2 p777 and p861 says:

"The macro with-accessors can be used to establish a lexical environment
in which specified slots are lexically available through their accessors
as if they were variables.  The macro with-accessors invokes the
appropriate accessors to access the specified slots."

However, the syntax of with-accessors doesn't specify slots (except implicitly
by virtue of the accessor presumably reading/writing a slot-value somewhere).

Would the following contrived example (note the complete lack of slots) 
be 'legal' CLOS code?

(defclass A ()
  ())

(defmethod foo ((arg A))
  (format t "~&Calling foo on ~A~%" arg)
  0)

(defmethod (setf foo) (new-value (arg A))
  (format t "~&Calling (setf foo) on ~A with new value ~A~%" arg new-value)
  new-value)

(defun bar ()
  (let ((A (make-instance 'A)))
    (with-accessors ((f foo)) A
      (incf f))))