On Thu, Aug 17, 2017 at 3:25 PM, Matt Price <moptop99@gmail.com> wrote:

> I'd love to be able generate dates dynamically using the {{{n}}} org
> macro, or some other mechanism.  I don't immediately see how that would be
> possible but maybe someone can guide me.  I'd want to do something
> equivalent to this pseudo-elisp:
>
> (let ((base-date 2017-09-05))
>   (+ base-date (* 7 {{{n}}}))
>
> I haven't looked into how date objects are parsed in org-mode, though, so
> I have no idea how hard it would be to actually implement something like
> this.
>

I made some progress on this (but not much).

I defined a simple macro that adds times together and creates a timestamp
that org can read -- in fact, this one adds some text as well:

#+MACRO: w (eval (format-time-string "Week {{{n(week)}}} (<%Y-%m-%d %a>)"
(time-add (encode-time 0 0 0 17 9 2017) (days-to-time (* 7 1)))) )

This does everything that I want *except* dynamically adding time to the
previous macro call.  I tried defining a dynamic version:

#+MACRO: w (eval (format-time-string "Week {{{n(week)}}} (<%Y-%m-%d %a>)"
(time-add (encode-time 0 0 0 17 9 2017) (days-to-time (* 7 $1)))) ))

And then calling it with

{{{w({{{n}}})}}}

But unsurprisingly and appropriately, that didn't work.

I also took a look at the patch Nicolas used to implement the {{{n}}} macro
(I've reattached it here for convenience only!).  It defines
`org-macro--counter-initialize` and calls it from inside
`org-macro-templates-initialize`.  I guess I could copy that strategy but
then I'd be maintaining my own copy of org-macro-templates-initialize,
which seems like a terrible idea.

So, I'm not sure how best to proceed. For my specific use-case, something
like this would be a huge timesaver when multiplied over semesters/years.
But I also wonder whether maybe other people would enjoy being able to do
date arithmetic inside org files (and outside of tables -- I know from
Sacha's 2015 blog post  that this is possible inside a table --
http://sachachua.com/blog/2015/06/using-your-own-emacs-lisp-functions-in-org-mode-table-calculations-easier-dosage-totals/).
If other people would also use such code, I could try to hack something
together for submission. Generalizable functions will be hard for me to
write because I am sometimes a bit dense. I would love to hear suggestions
from the group...


> Thank you everyone!
>

^^ this still applies!
Matt