I want to call org-update-radio-target-regexp as soon as org-mode recognises that a new <<<radio target>>> has been created (which seems to happen as soon as the third ">" is typed, at least this is when it gets fontified).

What hook can I use to get this done?

2 Answers 2


Following NickD's input on my first answer (thanks @NickD) I think a better approach is to limit org-update-radio-target-regexp to only fire when the target is first created. This is done by binding the ">" key and then testing whether point is just to the right of a <<<radio target>>> (after it is pressed). Here is the code:

(define-key org-mode-map (kbd ">")
  (lambda ()
    (if (and (org-in-regexp org-target-regexp)
             (not (org-in-regexp org-target-regexp nil t)))
          (insert ">")
      (insert ">"))))
  • Instead of binding the key globally, you should bind it in org-mode-map only, since you only want it active in Org mode buffers. You can then simplify the function by throwing away the testing of the mode.
    – NickD
    Feb 8, 2021 at 14:21
  • Aha! Thanks NickD. All done.
    – Adam
    Feb 8, 2021 at 16:41
  • Nice job! I think this is much more efficient than your initial attempt.
    – NickD
    Feb 8, 2021 at 17:16

This works:

(defun org-at-radio-target-p ()
  (not (eq (org-in-regexp org-radio-target-regexp) nil)))

(add-hook 'post-command-hook 
      (lambda () 
        (when (org-at-radio-target-p)

I am not sure how efficient it is, hooking into post-command-hook. But it seems to work okay, so far...

  • 1
    The post-command-hook runs after every command: e.g. inserting a character in a buffer is done by the command self-insert-command, so the hook is going to run after every character you type in a buffer; BTW, that's any buffer, not just org mode buffers. If the buffer is large, you are going to be spending a lot of time looking for radio targets and even though the regexp is not particularly complicated, the searches are not free. If you find that when you type fast in a large buffer, emacs cannot keep up with your typing, then you have probably reached this limit.
    – NickD
    Feb 7, 2021 at 19:07
  • 1
    The doc string for post-command-hook says It is a bad idea to use this hook for expensive processing. If unavoidable, wrap your code in ‘(while-no-input (redisplay) CODE)’ to avoid making Emacs unresponsive while the user types.
    – NickD
    Feb 7, 2021 at 19:09
  • 2
    And as a minor point, (when (not (eq (foo) nil)) (do-something)) is equivalent to (when (foo) (do-something)) - you probably don't need the org-at-radio-target-p function.
    – NickD
    Feb 7, 2021 at 19:16
  • 1
    Finally (?), assuming that you want to check for radio targets only when you are in an Org mode buffer, you might want to write the hook function like this: (lambda () (when (eq major-mode 'org-mode) (when (org-in-regexp org-radio-target-regexp) (org-update-radio-target-regexp)))), so you only pay the penalty in Org mode buffers, not in every buffer. And in general, it is recommended that you name your hook functions: that makes it easier to delete them from the hook when the need arises.
    – NickD
    Feb 7, 2021 at 19:20
  • @NickD thanks. Have you tested this? I was not able to get this to work...
    – Adam
    Feb 7, 2021 at 20:23

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