elisp-demo-02.el

;; Narrowing -- use save-restriction
(defun my-what-line ()
  "Print the current line number (in the buffer) of point."
  (interactive)
  (save-restriction
    (widen)
    (save-excursion
      (beginning-of-line)
      (message "Line %d"
               (1+ (count-lines 1 (point)))))))

(defun replace-regexp-in-region (start end)
  (interactive "*r")
  (save-excursion
    (save-restriction
      (let ((regexp (read-string "Regexp: "))
            (to-string (read-string "Replacement: ")))
        (narrow-to-region start end)
        (goto-char (point-min))
        (while (re-search-forward regexp nil t)
          (replace-match to-string nil nil))))))

(defun display-first-60-chars-of-current-buffer ()
  (interactive)
  (save-restriction
    (widen)
    (message "%s" (buffer-substring-no-properties 1 60))))

(display-first-60-chars-of-current-buffer)