コマンド ad-activate-regexp, ad-deactivate-regexp

(setq x "*")
  => "*"
(defun foo ()
  (format "%s %s" "foo" x))
  => foo
(defadvice foo (around foo-around activate)
  (let ((x "hoge"))
    ad-do-it))
  => foo
(defun bar ()
  (format "%s %s" "bar" x))
  => bar
(defadvice bar (around bar-around activate)
  (let ((x "hoge"))
    ad-do-it))
  => bar
(foo)
  => "foo hoge"
(bar)
  => "bar hoge"
(ad-deactivate-regexp "foo")
  => nil
(foo)
  => "foo *"
(bar)
  => "bar hoge"
(ad-activate-regexp "foo")
  => nil
(foo)
  => "foo hoge"