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1.前言

本篇目的：Emacs记录每个代码步骤，可以回退和前进，这样我们每一步都能在掌控之中，快速回退，这里不是代码回退，而是每个步骤可以回退。

2.安装步骤

<1>.源码

;;; Code:
(eval-when-compile (require 'cl))

(defvar point-undo-list nil)
(make-variable-buffer-local 'point-undo-list)

(defvar point-redo-list nil)
(make-variable-buffer-local 'point-redo-list)

(defun point-undo-pre-command-hook ()
  "Save positions before command."
  (unless (or (eq this-command 'point-undo)
              (eq this-command 'point-redo))

    (let ((cell (cons (point) (window-start))))
      (unless (equal cell (car point-undo-list))
       (setq point-undo-list (cons cell point-undo-list))))
    (setq point-redo-list nil)))
(add-hook 'pre-command-hook 'point-undo-pre-command-hook)

(defun point-undo-doit (list1 list2)
  ;; list1, list2 = {point-undo-list, point-redo-list}
  (destructuring-bind (pt . wst)
      (or (car (symbol-value list1)) '(nil)) ;nil-safe
    (when pt
      (set list1 (cdr (symbol-value list1)))
      (set list2 (cons (cons (point) (window-start)) (symbol-value list2)))
      (goto-char pt)
      (set-window-start (selected-window) wst))))

(defun point-undo ()
  "Undo position."
  (interactive)
  (point-undo-doit 'point-undo-list 'point-redo-list))

(defun point-redo ()
  "Redo position."
  (interactive)
  (when (or (eq last-command 'point-undo)
            (eq last-command 'point-redo))
    (point-undo-doit 'point-redo-list 'point-undo-list)))

;;;; Bug report
(defvar point-undo-maintainer-mail-address
  (concat "rubiki" "tch@ru" "by-lang.org"))
(defvar point-undo-bug-report-salutation
  "Describe bug below, using a precise recipe.

When I executed M-x ...

How to send a bug report:
  1) Be sure to use the LATEST version of point-undo.el.
  2) Enable debugger. M-x toggle-debug-on-error or (setq debug-on-error t)
  3) Use Lisp version instead of compiled one: (load \"point-undo.el\")
  4) If you got an error, please paste *Backtrace* buffer.
  5) Type C-c C-c to send.
# If you are a Japanese, please write in Japanese:-)")
(defun point-undo-send-bug-report ()
  (interactive)
  (reporter-submit-bug-report
   point-undo-maintainer-mail-address
   "point-undo.el"
   (apropos-internal "^point-undo-" 'boundp)
   nil nil
   point-undo-bug-report-salutation))

(provide 'point-undo)

;; How to save (DO NOT REMOVE!!)
;; (emacswiki-post "point-undo.el")
;;; point-undo.el ends here

<2>.配置

;;https://github.com/emacsmirror/point-undo

(load-file "~/.emacs.d/site-lisp/point-undo.el")
(require 'point-undo)
(global-set-key (kbd "o") 'point-undo)//回退
(global-set-key (kbd "p") 'point-redo)//前进