Re: Emacs Calendar - Removing holidays

[Christopher Dimech <dimech@gmx.com>]

> Sent: Thursday, November 19, 2020 at 9:50 PM
> From: "Michael Heerdegen" <michael_heerdegen@web.de>
> To: "Christopher Dimech" <dimech@gmx.com>
> Cc: "Jean Louis" <bugs@gnu.support>, help-gnu-emacs@gnu.org
> Subject: Re: Emacs Calendar - Removing holidays
>
> Christopher Dimech <dimech@gmx.com> writes:
>
> > Correct.  But then I have additional dates I want marked anh have put them
> > as holidays, but cannot get the christian, hebrew etc to stop showing.
>
> I think I see now why your attempts failed.  Emacs consults the variable
> `calendar-holidays' - and only that, when marking holidays.  When that
> variable is initialized, the bindings of all the holiday-... variables
> are appended.  That means that changing any of these variables later
> does not have an effect.
>
> So what you want is to change or customize `calendar-holidays' I think,
> e.g. by appending only some those holiday-... var values, or specifying
> your own stuff etc.  The variable should be bound to a list of holiday
> style diary expressions, that's the only requirement.
>
> You could also add the lunar phases there, but I don't think that would
> allow you to change the color of the highlighting, you are limited to
> one highlighting style.
>
> Let me add: the code of calendar and diary is old, written in a style
> that is ok but nobody would write it like that today.  And it has not
> been touched that much in the last years, probably because we also have
> org-mode now (and the agenda views, which offer a super set of calendar
> features).  That means that the behavior is sometimes a bit more 70s
> like than that of newer stuff.
>
> I'm a fan of diary symbolic expressions.  They allow you to specify
> anything that Lisp allows, quite powerful.  org-mode also supports using
> them in time stamps or so.

Could you give some examples of "diary symbolic expressions" and how they
would be useful for setting work dates.  I am particularly interested in
marking dates that are available for deadlines, meetings.  And another for
those already set with deadlines, meetings, etc.

> Michael.
>