Hi Dan,
general comparison operators for properties should have been
implemented a long time ago, thanks for bring this up. This is now
available in the GIT repository and will be part of the upcoming 6.02
release - thanks for raising this point.
Unfortunately there are no good examples for true custom searches
available. Some of this is described in the manual. Basically, you
need to use a general search to pre-select some entries, for example a
tags/property search with the criterion "LEVEL>=2" (this already uses
the new operators, so in order to do this, make sure you have the
latest devellopment version...). Then you need to write a function
that will decide if the entry at point should really be included, and
if not, where to continue the search. A short description of this
with a small example can be found here:
http://orgmode.org/manual/Special-agenda-views.html#Special-agenda-views
HTH
- Carsten
On Apr 17, 2008, at 2:19 PM, Dan Davison wrote:
I'd like to ask about ways in which (sorted) sparse trees can be
produced based on numerical-valued properties. One thing I have in
mind is that it would seem natural to treat priority as a (1-
dimensional) numerical quantity, rather than as a categorical
variable as it seems to be currently. i.e. I'm attracted by the idea
of being able to generate a sparse tree containing all subtrees with
priority greater than 2.5, and to have headings in the sparse tree
sorted by priority. (Of course I'm not suggesting replacing the
current priority system; in the above by 'priority' I mean some user
defined numerical-valued property.) [ Am I right in thinking that
one also can't do this currently with timestamps? Not that that is
necessarily needed as the agenda view does a lovely job. ]
So one version of my question would be
q1. Would it be possible to implement binary comparison operators
>,<,>=,<= for use in tag and property searches? (If true numeric
comparisons are difficult, then alphanumeric would still be useful.)
Sorry if this is available already.
I also have a more general question, which may well arise from my
ignorance of what's available. I should admit at the outset that so
far I haven't attempted to do anything other than completely basic
customisations of org-mode.
q2: It's my impression that the majority of current users aren't
scared of (e)lisp. (personally I am skill/knowledge-less but not
scared). Is there a 'template'/'model' function a user should look
at if they wanted to implement their own sparse-tree creation
function? I am thinking of a function that takes as arguments a
node's properties (and possibly also tags, priority, timestamps),
and computes a TRUE/FALSE value (err, t/nil?) that specifies whether
the subtree rooted at that point should be included in the search
results. I've seen the section in the manual 'using the property
API'; perhaps what I'm talking about is an extension to that API. If
all users had to do were provide a predicate function include-
subtree-in-sparse-tree, and org-mode deals with the tree traversal,
producing the formatted output, etc, then perhaps it wouldn't be
that hard for a user to implement something new like the >
operators? Perhaps. Having said all that, of course I do appreciate
the nice intuitive syntax for performing tag/property searches. I
was just wondering about a general way of making it easy for users
to extend the search functionality, and perhaps reduce the burden on
the main developer of responding to requests like my q1.
Dan
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