Emacs: load package only for given major mode in init.el

Question

I made some time ago a .el file (epx.el) for some files with a specific format that I am using. I load it in my init.el through (require 'epx) .

The problem is that in this epx.el, there is:

(defadvice comment-region (after indent-after activate)
  (indent-region beg end)
  )
(defadvice uncomment-region (after indent-after activate)
  (indent-region beg end)
  )

I got trouble because it affects the behavior of the comment functions (such as comment-dwim ) in other major modes (in particular in the python mode: when I uncomment a commented region, it breaks my indentation...). If I comment these lines in epx.el, there is no more problems.

So how could these (defadvice ...) only have effect in the epx major mode?

Thanks!

Answer 1

You could check the major mode of the current buffer, and take action only if it's exp-mode :

(defadvice comment-region (after indent-after activate)
  (if (derived-mode-p 'exp-mode)
      (indent-region beg end))
  )
(defadvice uncomment-region (after indent-after activate)
  (if (derived-mode-p 'exp-mode)
      (indent-region beg end))
  )

EDIT: use derived-mode-p as suggested by @Stefan.