elisp *scratch* の永続化

scratch.el

(setq initial-scratch-message "")           ; とりあえず initial message を消す
(add-hook 'kill-emacs-hook 'scratch-save)   ; Emacs終了時に *scratch* を保存
(add-hook 'window-setup-hook 'scratch-resume); 起動時に.scratchを読み込み
;;  window-setup-hook が最後に呼ばれるっぽい
;;  @see info 38.1.1 Summary: Sequence of Actions at Startup
(add-hook 'kill-buffer-hook; *scratch* バッファで kill-buffer したら内容を保存
          (lambda () (if (equal (buffer-name) "*scratch*") (scratch-save))))
(add-hook 'after-save-hook        ; *scratch*をファイル保存したら、*scratch*復帰
          (lambda () (unless (get-buffer "*scratch*") (scratch-resume))))
(defvar scratch-file "~/.emacs.d/.scratch")
(defvar scratch-file-bakup (concat scratch-file ".bak"))
(defun scratch-save ()
  "*scratch* を保存する"
  (interactive)
  (let ((buf (get-buffer "*scratch*")))
    (when buf
      (copy-file scratch-file scratch-file-bakup t t) ; bakup
      (set-buffer buf)
      (write-file scratch-file)
      (ignore-errors (kill-buffer ".scratch")))))
(defun scratch-resume ()
  "*scratch* を保存した内容で復帰する"
  (interactive)
  (if (eq 0 (nth 7 (file-attributes scratch-file))) ; if file size is zero
      (copy-file scratch-file-bakup scratch-file t t)) ; fail safe
  (set-buffer (get-buffer-create "*scratch*"))
  (funcall initial-major-mode)
  (insert-file-contents scratch-file nil nil nil t)
  (ignore-errors (kill-buffer ".scratch")))