M. Rincón Guided by asteriks

Viewing Important Dates in Emacs

2022-16.05 Revised: 2022-17.05

For a while I tried to use org-mode to schedule appointments and keep track of my calendar. But eventually I gave up. I never found an effective way to coordinate with others. I still use Emacs to mark non-calendar-blocking events like market half days. My phone can easily keep track of regular events like birthdays. But recurrent events with more complicated rules are a pain. For example, crude oil futures expire the third business day before the 25th day of the month if the 25th is a business day, or the fourth prior day if the 25th is a holiday. Adding those dates to Outlook is a bit frustrating. So for those days I still use Emacs along with a small personal package with some additional date functions1.

The library provides just two public functions. The functions are just additional sexp entries for the calendar. The first marks the start of my workweek. The second takes some rules and marks the dates that match the rules. For example, if I want to find the last work day of the month according to U.S. federal calendar, I can add this line to my diary:

 ;; -*- mode: diary; mode: auto-revert; -*-
 %%(df-diary-expirations 1 -1) Last work day of the month

Or I can mark the last work day before the 25th of every month according to a different calendar:

 %%(df-diary-expirations 25 -1 df-globex-holidays) Work day before the 25

Or something even more complicated, like finding the first work day on or before the 25th, and then mark the third work day before that day with a special color:

 %%(df-diary-expirations 25 -3 df-globex-holidays t personal-face) Hello

Now I can open the calendar with M-x calendar, press m and the days that match the rule are colored with whatever color I choose. I can also press d and get some information on the date, in this case the string "Hello".

To display the events in the fancy org-mode agenda along with holidays, I added the following to my configuration:

 (setq org-agenda-include-diary t)

1This program comes with absolutely no warranty.