Set custom keybinding for specific Emacs mode

Question

Though I know how to set a global key-binding in Emacs, I find it hard to even Google out the code for a local (minor-mode specific) key-binding. For instance, I have this code in my .emacs:

;; PDFLaTeX from AucTeX
(global-set-key (kbd "C-c M-p")
        (lambda ()
          (interactive)
          (shell-command (concat "pdflatex " buffer-file-name))))

I don't want to set it globally. Is there a function like local-set-key?

More and more I find myself going to the Emacs Wiki for help: http://www.emacswiki.org/emacs/KeyBindingDiscussion There it shows that you can add a key binding to a mode key map and also shows how to find that map. — drysdam, Mar 31 '11 at 12:50
Yepp... I saw that one already, but I get `Symbol's value as variable is void: LaTeX-mode-map` all the time. Hmmm... — aL3xa, Mar 31 '11 at 13:30

score 52 · Answer 1 · answered Jan 09 '13 at 08:03

52

I use the following:

(add-hook 'LaTeX-mode-hook
          (lambda () (local-set-key (kbd "C-0") #'run-latexmk)))

to have a bind defined for LaTeX mode alone.

answered Jan 09 '13 at 08:03

Dror

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The `#` was redundant with me. – doctorate Jan 07 '15 at 09:01
I had to set `'latex-mode-hook` instead (no caps). I also found the `#` unnecessary. – hunse Apr 29 '15 at 21:10
10

On sharp quoting #' http://endlessparentheses.com/get-in-the-habit-of-using-sharp-quote.html – codeasone Feb 16 '16 at 12:53

score 49 · Accepted Answer · edited Nov 06 '18 at 22:44

49

To bind a key in a mode, you need to wait for the mode to be loaded before defining the key. One could require the mode, or use eval-after-load

   (eval-after-load 'latex 
                    '(define-key LaTeX-mode-map [(tab)] 'outline-cycle))

Don't forget either '—eval-after-load is not a macro, so it needs them.

edited Nov 06 '18 at 22:44

Evgeniy Berezovsky

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answered Mar 31 '11 at 20:24

Rémi

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How do you determine the first argument to `eval-after-load` programmatically? – ealfonso Sep 26 '13 at 18:01
I think it's enough to provide any function which belongs to the mode – e.g. `'LaTeX-mode` instead of `'latex` would do just as well. – Emily Sep 26 '14 at 18:51
For me the variable is called latex-mode-map (all lower case). LaTeX-mode-map doesn't exist. – Anton Eliasson Nov 30 '14 at 09:26
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`[(tab)]` is old syntax for `(kbd "TAB")` – Lenar Hoyt Nov 26 '15 at 10:50
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@LenarHoyt: actually, no: `[(tab)]` is the same as `[tab]` which is the key-sequence sent when you hit the `TAB` key in the GUI version of Emacs. `(kbd "TAB")` OTOH is the same as `[?\t]` which is the key-sequence sent when you hit that same `TAB` key in a text terminal (which is also the same key-sequence sent when you hit `C-i`). The two options are "unified" inside Emacs by `function-key-map` which remaps `[tab]` to `(kbd "TAB")` if there's no binding to `[tab]`. So if you want your binding to work both in a GUI and in a tty, better use `(kbd "TAB")`. – Stefan Oct 25 '17 at 18:09

score 10 · Answer 3 · answered Mar 31 '11 at 12:58

You need to identify the key map for that mode (for example, LaTeX-mode-map) and use the function define-key. As an example, along with activating outline-minor-mode within LaTeX mode, I have:

  (define-key LaTeX-mode-map [(tab)] 'outline-cycle))

In this case the major mode (LaTeX) holds the key binding, but there is also an outline-minor-mode-map.

score 4 · Answer 4 · 2022-04-30T22:40:00.037

None of the other answers satisfied my needs. So this may help other people. I wanted Tab to jump to the beginning of the line if I'm in Evil's normal mode (basically this means everywhere in Emacs), but I instead wanted it to cycle between org item states if I am in an org-mode document.

One option was to mess around with separate bindings and constant binding-rebinding whenever I switched buffers (because evil allows only one binding per key in its normal state).

But a more efficient option was to make Tab run my own code which runs the required function based on which major mode the current buffer uses. So if I am in a org buffer, this code runs org-cycle, and otherwise it runs evil-first-non-blank (go to the first non-whitespace character on the line).

The technique I used here can also be used by calling your custom function via global-set-key instead, for people who use regular non-evil Emacs.

For those who don't know Emacs lisp, the first line after the "if" statement is the true-action, and the line after that is the false-action. So if major-mode equals org-mode, we run org-cycle, otherwise we run evil-first-non-blank in all other modes:

  (defun my/tab-jump-or-org-cycle ()
    "jumps to beginning of line in all modes except org mode, where it cycles"
    (interactive)
    (if (equal major-mode 'org-mode)
        (org-cycle)
      (evil-first-non-blank))
    )
  (define-key evil-normal-state-map (kbd "<tab>") 'my/tab-jump-or-org-cycle)

Set custom keybinding for specific Emacs mode

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