怎样对 Emacs 内置的函数进行 advice

[sonchonjay]

emacs的dired功能很强大，但是在目录跳转的时候会产生很多buffer，虽然用a进入可以避免，但是^回原目录的时候还是会产生新buffer。在网上搜索了一下说可以通过对内置函数进行advice来实现单buffer。代码如下：

(defadvice dired-find-file (around dired-find-file-single-buffer activate)
"Replace current buffer if file is a directory."
(interactive)
(let ((orig (current-buffer))
(filename (dired-get-file-for-visit)))
ad-do-it
(when (and (file-directory-p filename)
(not (eq (current-buffer) orig)))
(kill-buffer orig))))
(defadvice dired-up-directory (around dired-up-directory-single-buffer activate)
"Replace current buffer if file is a directory."
(interactive)
(let ((orig (current-buffer)))
ad-do-it
(kill-buffer orig)))

我的问题是不知道怎么进行advice，直接新建一个.el的文件还是怎样？
请做过相关设置的高手不吝赐教！

[zhan]

写进 .emacs 吧

[sonchonjay]

直接写进去吗？好，我试试

[redflow]

用dired-single就可以了