Open current file as root

Don't think I've written this one myself and I don't remember where it comes from. Oh well.

(defun sudo-edit (&optional arg)
  "Edit currently visited file as root.

With a prefix ARG prompt for a file to visit.
Will also prompt for a file to visit if current
buffer is not visiting a file."
  (interactive "P")
  (if (or arg (not buffer-file-name))
      (find-file (concat "/sudo:root@localhost:"
                         (ido-read-file-name "Find file(as root): ")))
    (find-alternate-file (concat "/sudo:root@localhost:" buffer-file-name))))