[Orgmode] Re: Timestamp format questions

[Matt Lundin]

Hi Joost,

Joost Kremers <address@hidden> writes:

> Most pressing: how can I say that a certain event occurs every week on
> a certain day and time, but only for a limited period? E.g., for
> classes I teach I want to be able to say 'this class takes place from
> April 8 through July 8, every Thursday from 12.00 to 14.00. If I
> write:
>
>    <2010-04-08 Thu 12:00-14.00 +1w>
>
> I get the correct time and interval, but of course it doesn't stop at the
> correct date. However, if I write
>
>    <2010-04-08 Thu 12:00-14.00 +1w>--<2010-07-08 Thu>
>
> then it shows up *every day* in the agenda view, not just on Thursdays. (That
> actually looks like a bug to me, but perhaps I'm doing something
> wrong.)

You can use diary sexps to schedule more complex appointments.

,---- (info "(org) Timestamps") 
| DIARY-STYLE SEXP ENTRIES
|      For more complex date specifications, Org mode supports using the
|      special sexp diary entries implemented in the Emacs calendar/diary
|      package.  For example
| 
|           * The nerd meeting on every 2nd Thursday of the month
|             <%%(diary-float t 4 2)>
`----

See also the following FAQ entry:
http://orgmode.org/worg/org-faq.php#diary-sexp-in-org-files

The function org-diary-class nicely covers the scenario above:

--8<---------------cut here---------------start------------->8---
* 12:00-14:00 Weekly class
<%%(org-diary-class 4 8 2010 7 8 2010 4)>
--8<---------------cut here---------------end--------------->8---

http://orgmode.org/worg/org-faq.php#org-diary-class

> Also, is there a way to say that a certain event that occurs every
> week does not occur on one specific date? For example, I teach a class
> every Thursday, but the Thu. 13th of May was Ascension Day, so the
> class was cancelled. I would like the event to not show up on such
> days.

--8<---------------cut here---------------start------------->8---
* 12:00-14:00 Weekly class
<%%(org-diary-class 4 8 2010 7 8 2010 4 19)>
                                        ;; iso number of the week to skip
--8<---------------cut here---------------end--------------->8---

Best,
Matt