How do I “group” hooks?

Question

There are certain things like the display of trailing whitespace, display of buffer boundaries, rainbow-colored delimiters and many more I'd like to enable in most modes or rather, all programming- and text-related ones (because displaying trailing spaces in, say ediff-mode, would clash with the major mode) instead of using a globalized minor mode with exception rules. Since most modes are derived from either prog-mode or text-mode, adding the function in question to both prog-mode-hook and text-mode-hook does work, however there are enough modes not following this specification, such as css-mode or LaTeX-mode.

I'd like to define a hook that encompasses all these modes for the time being to only add functions to one hook. Let's call it non-special-mode-hook (to distinguish it from special-mode-hook). How would I be able to create such a hook that is run for all major modes it is made for?

Answer 1

Just group those settings together into a function, and add that function to all of the relevant hook functions:

(defun my-non-special-mode-setup ()
  (setq show-trailing-whitespace t)
  ...)
(dolist (hook '(prog-mode-hook text-mode-hook css-mode-hook ...))
  (add-hook hook 'my-non-special-mode-setup))

No other way to do this would be more concise: whatever happens, somewhere you're going to have either a whitelist or blacklist of modes. In practice, you'll only find a few modes which need adding to the list, so I'd suggest just keeping things simple.

In my own config, I use exactly this trick to unify the configuration of several lisp-oriented modes.

Answer 2

You could add a function to after-change-major-mode-hook, that checks whether the new mode is an interesting one (possibly through (not (derived-mode-p 'special-mode))), and if so runs non-special-mode-hook.

Answer 3

I found myself often doing @sanityinc's pattern of wrapping my settings and minor mode activations in a defun and looping through hooks to call it, but I wanted a cleaner approach so I wrote this macro:

(defmacro hook-modes (modes &rest body)
  (declare (indent 1))
  `(--each ,modes
     (add-hook (intern (format "%s-hook" it))
               (lambda () ,@body))))

Note: I'm dash.el for cleanliness but it could easily be adapted to use (dolist).

Then you can define grouped modes as list variables and use it like so:

(defvar progish-modes
  '(prog-mode css-mode sgml-mode))

(hook-modes progish-modes
  (highlight-symbol-mode)
  (highlight-symbol-nav-mode))

Answer 4

Rather than define a new hook that works for all these non-derived modes you can do the following.

(defun run-my-hooks ()
  "Run all the following functions in the hook"
  (smartparens-mode 1)
  (whitespace-mode 1)
  (my-needed-mode 1)
  ...)

(add-hook 'specific-mode-hook 'run-my-hooks)
(add-hook 'another-mode-hook 'run-my-hooks)

You'll still need to add it to all the modes, but by defining your function to include all the modes you will only have to change one definition when adding/removing addtional features.

Answer 5

Maybe you can try this:

(setq lisp-dialects-mode-hook '(lisp-mode-hook
                            lisp-interaction-mode-hook
                            emacs-lisp-mode-hook
                            ;; common-lisp-mode-hook
                            scheme-mode-hook
                            clojure-mode-hook
                            cider-repl-mode-hook
                            ))

(add-hook 'lisp-dialects-mode-hook 'func)