Emacs Carnival: diary, Part 2

As I wrote earlier, I consider diary to be an underappreciated Emacs built-in.

I got interested in it again when I wanted to schedule a recurring meeting in Org for the third Tuesday of every month. I saw on Reddit that some folks use diary-float in place of the usual active timestamp to achieve this. So I added this after the meeting header to make it work:

  * Third Tuesday of the Month Club
  SCHEDULED: <(%%diary-float t 2 3) 19:00-20:00>

I have five meetings that use this method of automatic scheduling. I like this approach because of its simplicity and elegance. Unfortunately, it doesn't behave the same way as a recurring task.

When I mark a recurring task as complete, Org reschedules it for the next date on which it should occur. And it changes DONE to TODO to ensure the event shows up on the agenda for the next occurrence.

This doesn't happen for a task that's scheduled with diary-float. When marked complete, the headline remains at DONE; the next event won't show up on the agenda.

And so Fengyuan Chen wrote next-day-spec¹ to solve this issue. Unfortunately it doesn't work with the latest versions of Emacs.

One of the many recognized cognitive biases is called the Sunk Cost Fallacy², which impels an individual to favor an inferior (or incorrect) solution because a significant amount time, money, and/or effort has been invested in the solution. Well, I've invested time and effort in both diary-float and next-day-spec, so I've continued to endorse it as a solution.

But even if rescheduling did work, I think it's better to have each meeting scheduled as a subheading of the overall meeting topic, like this:

  * Third Tuesday of the Month Club
  ** DONE May 2026: <2026-05-19 Tue>
    :LOGBOOK:
    CLOCK: [2026-05-19 Tue 18:54]--[2026-05-19 Tue 20:12] =>  1:18
    :END:
    - Note taken on [2026-05-19 Tue 21:20] \\
    We ate pizza.  Again.
    ** TODO June 2026: <2026-06-23 Tue>
      ** TODO July 2026: <2026-07-21 Tue>

The advantage to this is that clocked time and notes are organized neatly within each individual subtopic, not aggregated into one logbook and a series of notes. If the aggregated time is desired, one could insert the log report. I'll review this in another post.

But it's fun to schedule events that occur on irregular dates, such as National Engineers Week (US), which is the week in which George Washington's birth anniversary occurs³. Here's how you can add it to an Org file:

  * TODO Celebrate Engineers Week!
  SCHEDULED: <%%(equal (calendar-gregorian-from-absolute (calendar-dayname-on-or-before 0 (calendar-absolute-from-gregorian (list 2 22 (calendar-extract-year date))))) date)>

Do you have a favorite use for dairy?

¹ https://github.com/chenfengyuan/elisp/blob/master/next-spec-day.el
² Sunk cost - Wikipedia
³ https://www.holidayscalendar.com/event/national-engineers-week/