Make anchors in Org more useful

1 files changed, 41 insertions, 0 deletions

@@ -1488,6 +1488,47 @@ I’ve put org mode under Applications, as opposed to Writing, because it’s  m
       (add-hook 'emacs-lisp-mode-hook #'org-link-minor-mode)
     #+end_src
 
+*** Useful HTML Anchors
+
+    #+begin_src emacs-lisp
+      (defun my/ensure-headline-ids (&rest _)
+        "Ensure better headlines for Org trees.
+
+      Use CUSTOM_ID property, or barring that, a \"fixed\" title.
+
+      All non-alphanumeric characters are cleverly replaced with ‘-’.
+
+      If multiple trees end-up with the same id property, issue a
+      message and undo any property insertion thus far.
+
+      E.g., ↯ We'll go on a ∀∃⇅ adventure
+         ↦  We'll-go-on-a-adventure
+      "
+        (interactive)
+        (let ((ids))
+          (org-map-entries
+           (lambda ()
+             (org-with-point-at (point)
+               (let ((id (org-entry-get nil "CUSTOM_ID")))
+                 (unless id
+                   (thread-last (nth 4 (org-heading-components))
+                     (s-replace-regexp "[^[:alnum:]']" "-")
+                     (s-replace-regexp "-+" "-")
+                     (s-chop-prefix "-")
+                     (s-chop-suffix "-")
+                     (setq id))
+                   (if (not (member id ids))
+                       (push id ids)
+                     (message-box "Oh no, a repeated id!\n\n\t%s" id)
+                     (undo)
+                     (setq quit-flag t))
+                   (org-entry-put nil "CUSTOM_ID" id))))))))
+
+      ;; Whenever html & md export happens, ensure we have headline ids.
+      (advice-add 'org-html-export-to-html   :before 'my/ensure-headline-ids)
+      (advice-add 'org-md-export-to-markdown :before 'my/ensure-headline-ids)
+    #+end_src
+
 ** Git
 
 #+begin_src emacs-lisp