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I use org-num-mode to have headlines with a numbering 1.1.1 or 1.2.1... etc

When I use org-insert-link, I want the default description to be this number. For now, it is the text in the headline but I would much prefer the number to be the default setting.

I think if I can get the numbering for a given headline I should be able to cook up something using this thread but I did not find how to get the current headline's numbering.

EDIT: as indicated in the comments, for this to work I must most likely use an export hook to get the section numbers at export time.

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  • What happens if you introduce another headline between two of the old headlines? I presume that the numbers change but the links wouldn't. Are you sure you want that?
    – NickD
    Apr 15, 2022 at 21:30
  • You are right I would not want that. Maybe a post-processing like org-export-before-parsing would do the trick. I guess the link would have dummy names that are then replaces in the org-export-before-parsing hook. I am a bit new to elisp but I think this should be doable.
    – TMat
    Apr 16, 2022 at 7:30

1 Answer 1

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+50

From org-num--make-overlay we find that org-nume-mode does not insert extra contents in a buffer, but only creates the numbers as overlays (via the 'after-string' property). So, to get the numbers, you should get the appropriate property of that overlay. The following function provides an example for how to achieve what you want:

(defun org-replace-links-descs (&rest _) ; accepts, any number of 'unused'; arguments
  (interactive)
  (if (not org-num-mode)
      (message "org-num-mode not active")
    (goto-char (point-min))
    (while (not (stringp (org-next-link)))
      (let* ((context (org-element-context))
             (beg (org-element-property :begin context))
             (end (org-element-property :end context))
             (cbeg (org-element-property :contents-begin context))
             (cend (org-element-property :contents-end context))
             (raw-link (org-element-property :raw-link context))
             file
             num)
        (when (string-match  "\\(^*\\|:\\*\\)" raw-link)
          (save-excursion
            (org-link-open context)
            (unless org-num-mode (org-num-mode))
            (skip-chars-forward "*")
            ;; there can be multiple overlays so we filter out 'org-num' overlay
            (when (string-match "^file" raw-link)
              (setq file (nth 1 (split-string raw-link ":"))))
            (setq num (substring
                       (car
                        (delete nil
                                (mapcar (lambda (o)
                                          (when (overlay-get o 'org-num)
                                            (overlay-get o 'after-string)))
                                        (overlays-at (point)))))
                       0 -1)))
          (let ((new-desc (concat file (when file ":") num)))
            (if cbeg
                (replace-region-contents cbeg cend (lambda () new-desc))
              (goto-char (1- end))
              (insert "[" new-desc "]"))))))))

(defun my-org-export-dispatch ()
  (interactive)
  (when org-num-mode
    (org-replace-links-descs))
 (org-export-dispatch))

Now, you can call the org-replace-links-descs function 'manually' before export, or you can create a custom function, where you call org-replace-links-descs before you export function, like in the my-org-export-dispatch example, to 'trigger' the export (another option would be to advise the export function, but if using a 'custom export function' is an option, then that would be the easiest solution).

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  • I tried to add this to the export using (add-hook 'org-export-before-parsing-hook #'org-replace-links-descs) but it did not work. Could you explain more what this function do ? How can I use it (i.e. will it change the description of any link I do ? How must I do the link in order for it to be recognized by your code ? ).
    – TMat
    May 9, 2022 at 17:34
  • As mentioned in the answer, you can call the function 'manually', i.e. via M-x, before export. There are two reasons why the function does not work in the hook. First, as mentioned in the hook's docstring, the hook passes a single argument when calling each function. Second, the function in the hook is executed in a copy of the original buffer where org-num-mode is not active. Therefore, you should execute the function in the original buffer before export. I have updated the answer.
    – dalanicolai
    May 9, 2022 at 19:25
  • To answer your other two questions, it should work on any link in your buffer, as long as you have inserted it using (the format as inserted by) org-insert-link.
    – dalanicolai
    May 9, 2022 at 19:45
  • Ok thanks. I tested and it does not work: it replaces the description with the number of the section in which the link is currently, it does not replace the description with the number from the target of the link.
    – TMat
    May 10, 2022 at 5:46
  • 1
    Thanks a lot, this work for me.
    – TMat
    May 10, 2022 at 16:17

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