模式本地缺陷

Question

Is it possible to modify function's behavior with defadvice for specific mode/buffer only? I want mouse-yank-primary to insert extra text, but only when i'm in specific mode. I've tried 'defadvice after' for mouse-yank-primary, but once activated it works in all other buffer as well.

I think it can be resolved by rebinding mouse button to my own function in mode hook, but elisp manual says it's better to use defadvice.

Answer 1

Rebinding the mouse button to another function seems preferable to me. You don't need a mode hook for that, usually you just modify the mode's keymap:

(eval-after-load '<mode>
  '(define-key <mode>-map [mouse-2] 'my-mouse-yank-primary))

Localizing an advice to a major mode is a bit harder. There's no argument you can pass to defadvice to do that, but you can set some variable's buffer-local value in a mode hook, and then check this value in the advice code. If it's set, do something special. If not, just evaluate ad-do-it .

Answer 2

Localizing an advice to a major mode is easy:

(defadvice foo (after bar activate)
  (when (derived-mode-p 'python-mode)
    (do (something) now)))