anchor.diff:                 (posix-error (c)
                    (handle-error c))
                  (:no-error (fd) fd))))
  -    (let ((fd (try-open)))
  +    (let ((fd (or handle (try-open))))
         (%set-fd-nonblock fd)
         (setf (handle-of device) fd)))
     (values device))
  
positive.code: ;;;-------------------------------------------------------------------------
  
  (defmethod initialize-instance :after
      ((device file-device) &key filename flags
       (mode *default-open-mode*) delete-if-exists)
    (setf (filename-of device) (copy-seq filename))
    (with-device (device)
      (device-open device :filename filename :flags flags
                   :mode mode :delete-if-exists delete-if-exists)))
  
  
negative.code: ;;;-------------------------------------------------------------------------
  
  (defmethod device-open ((device file-device)
                          &key handle filename flags mode delete-if-exists)
    (labels ((handle-error (c)
               (posix-file-error c filename "opening"))
             (try-delete ()
  