[Orgmode] thoughts: "formulas for timestamps" feature

[Ruslan Kosolapov]

Hi all, it's me again :)

My previous message
(http://www.mail-archive.com/address@hidden/msg01685.html)
contains complains about ability to use formulas for timestamp (third
problem).

Yesterday I found http://www.cs.brown.edu/~gmarceau/spread.el

I think it is what I need.  But one small problem blocks me.

In org-file I wrote:
** NEW Task1
   DEADLINE: qwe <= (concat "<2007-05-15 Втр>") => task1

After M-x spread-recalc org file goes to:
** NEW Task1
   DEADLINE: "<2007-05-15 Втр>" <= (concat "<2007-05-15 Втр>") => task1

But agenda do not determine dates in quotes (btw, shift-up works
well).

I see two solutions:
 - fix regexp of dates determination for quotes support (in org-mode)
 - fix spread-mode - remove quotes printing

I tried to fix spread-mode, and fail (there are many reasons of it).

But if I change org-deadline-time-regexp as follows:
-         (concat "\\<" org-deadline-string " *<\\([^>]+\\)>")
+         (concat "\\<" org-deadline-string " *\"?<\\([^>]+\\)>\"?")
all works fine.

So, I have some questions:

1. Does org-mode uses symbols "<=" and "=>"?

2. Does org-mode contains functions for timestamp calculation?  I need
something like 
(add-to-timestamp "<2007-05-15 Втр>" "+1d") with result "<2007-05-16 Срд>"
Now I found only org-timestamp-change, but "Change the date in the
time stamp at point" is not what I need (I have no "point", I have a
string with timestamp).  Of course, I can write such functions by
myself, but it is not the true way if such functions already exists.

PS: I'm a newbie in emacs lisp, so, sorry if my second question is
a stupid one :)

-- 
Ruslan Kosolapov
Plesk QA Department Second Manager
SWsoft, Inc.