Add gist for an event handler for org mode tasks

gists.org

@@ -124,6 +124,36 @@ My vertico-repeat setup.
     (minibuffer-setup . vertico-repeat-save))
 #+end_src
 
+* Execute code on task state changes :emacs:org:
+
+#+begin_src org :tangle gists/execute-code-on-task-state-change.org
+  The function below executes Lisp forms stored in properties of a TODO item, when it reaches a certain state. The function is supposed to be added to the =org-after-todo-state-change-hook=.
+
+  The property should be named =ON_<STATE>= where =STATE= is a state defined in =org-todo-keywords=. See also the example task below.
+
+  ,#+begin_src elisp
+    (defun my/task-state-event-handler ()
+      "Called as part of org-after-todo-state-change-hook, which looks
+    for a property in the todo item at point and looks for properties
+    containing code that needs to be executed."
+
+      (if-let* ((state org-state)
+                (event-property-name (concat "ON_" state))
+                (properties (org-entry-properties))
+                (code-string (cdr (assoc event-property-name properties)))
+                (code (car (read-from-string code-string))))
+          (org-eval code)))
+
+    (add-hook 'org-after-todo-state-change-hook 'my/task-state-event-handler)
+  ,#+end_src
+
+  ,* TODO Example task
+  :PROPERTIES:
+  :ON_PROGRESS: (message "Busy!")
+  :ON_DONE:  (message "Done!")
+  :END:
+#+end_src
+
 * Meta
 ** License
 

gists/execute-code-on-task-state-change.org

@@ -0,0 +1,25 @@
+The function below executes Lisp forms stored in properties of a TODO item, when it reaches a certain state. The function is supposed to be added to the =org-after-todo-state-change-hook=.
+
+The property should be named =ON_<STATE>= where =STATE= is a state defined in =org-todo-keywords=. See also the example task below.
+
+#+begin_src elisp
+  (defun my/task-state-event-handler ()
+    "Called as part of org-after-todo-state-change-hook, which looks
+  for a property in the todo item at point and looks for properties
+  containing code that needs to be executed."
+
+    (if-let* ((state org-state)
+              (event-property-name (concat "ON_" state))
+              (properties (org-entry-properties))
+              (code-string (cdr (assoc event-property-name properties)))
+              (code (car (read-from-string code-string))))
+        (org-eval code)))
+
+  (add-hook 'org-after-todo-state-change-hook 'my/task-state-event-handler)
+#+end_src
+
+* TODO Example task
+:PROPERTIES:
+:ON_PROGRESS: (message "Busy!")
+:ON_DONE:  (message "Done!")
+:END: