Report time at whole hours by prompting mini-buffer

Question

Reference to 31.10.6 Appointments of Emacs Manual

It provides a handy solution to report hour and remind appointments:

For example, suppose the diary file contains these lines:
=M-x appt-add= adds entries to the appointment list without affecting your diary file. You delete entries from the appointment list with =M-x appt-delete=.

Then if set the minutes to warning as 0 minutes to remind whole hours, it becomes a alarm to report whole hour to prompt a mini-buffer.

For example, M-x appt-add a whole hour "9:00pm" and set the warning as 0 minute. When it comes to 9:00pm, a mini-buffer would be prompt to report the current time.
At this moment, appointment transforms itself as an alarm to report whole hours.

Unfortunately, the appointment is one-off and it's cumbersome to set alarms manually every day.

How could have an alarm to report whole hours using appointments or any alternative solutions?

Answer 1

You can do that using timers. Define a function to print out the time in the echo area:

(defun announce-time ()
  (message (format "The time is %s" (format-time-string "%H:%M" (current-time)))))

and set up a timer to run it at some initial time and every hour thereafter:

(run-at-time "00:00" 3600 #'announce-time)

You can cancel the timer if you don't want it any longer with M-x list-timers RET and pressing c on this timer.