Emacsで句読点を全角コンマと全角ピリオドに置き換える

(defun my/region-replace (str newstr begin end)

  "指定範囲内で置換を行う"

  (goto-char begin)

  (while (search-forward str end t)

    (replace-match newstr)))

(defun my/replace-with-comma-and-period ()

  "選択範囲内の句読点をコンマとピリオドに置き換える"

  (interactive)

  (let ((curpos (point))

        (begin (if (region-active-p)

                   (region-beginning) (point-min)))

        (end (if (region-active-p)

                 (region-end) nil)))

    (my/region-replace "。" "．" begin end)

    (my/region-replace "、" "，" begin end)

    (goto-char curpos)))