Running code after org-deadline

Question

I want to run code after adding a deadline, for example to move it forward by one day in case the deadline is early in the day, or by a few hours in case it's on a different time zone.

This attempt with a hook and a function is not called upon setting a deadline with C-d:

(defun my-org-deadline(&rest ignore)
  (interactive)
  (message "Called!!!!!")
  (let ((todo (org-get-todo-state))
        (deadline (org-entry-get nil "DEADLINE"))
        )

    ;; move deadline ahead by 1 day, to avoid missing it.
    (when (and todo deadline)
        (org-back-to-heading)
        (search-forward "DEADLINE: ")
        (org-timestamp-change -1 'day)
        )))

(add-hook 'org-deadline #'my-org-deadline)

The function works properly if I call it, but it is not called after setting a deadline.

What is the proper way to make code run after setting a deadline?

Answer 1

There is no hook called org-deadline. Most hooks are called <mumble>-hook so when you are looking for one, try C-h v org--hook and press TAB: that should give you a completion buffer with all the available hooks whose names start with org-.

Unfortunately, there is no hook defined to allow you to call a function after you set a deadline. But you can still use an advice: define your function to do what you want, and then add it as an after advice to org-deadline. Something like this should work with your my-org-deadline function:

(advice-add 'org-deadline :after #'my-org-deadline)

C-h f org-deadline will then tell you that this function has been advised. You can remove the advice with

(advice-remove 'org-deadline #'my-org-deadline)

---

NOTE: This SHOULD work I think, but it doesn't for me: I get a wrong-number-of-arguments error when org-deadline gets called. The error happens in various functions and I have not had time to debug the problem yet.

OTOH, I tried it on a different machine with slightly more recent emacs and it works fine:

GNU Emacs 28.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.24.13, cairo version 1.16.0) of 2020-10-30 Org mode version 9.4 (release_9.4-53-g23f941)

so I suspect the solution is fine in general: there must be something wrong with the emacs/org version on the other machine.