iedit-dwim.el

(defun iedit-dwim-get-string ()
  (cond ((iedit-region-active)
         (setq mark-active nil)
         (run-hooks 'deactivate-mark-hook)
         (buffer-substring-no-properties
          (region-beginning) (region-end)))
        (t
         (current-word))))
(defun iedit-dwim (arg)
  "Starts iedit but uses \\[narrow-to-defun] to limit its scope."
  (interactive "P")
  (if arg
      (iedit-mode)
    (save-excursion
      (save-restriction
        (widen)
        (cond (iedit-mode
               (iedit-done))
              (t
               (narrow-to-defun)
               (if (eq (count-lines (point-min) (point-max)) 1)
                   (widen))
               (iedit-start (iedit-dwim-get-string) (point-min) (point-max))))))))