[Tracker] Tags hierarchy and cascading delete

[THEVENET Florent <florent thevenet laposte net>]

Hello,

Trying to integrate Tracker in getting things gnome (gtg) I got some
problem.

First gtg features tags hierarchy.
To solve that I though we could add a property nao:hasChildrenTag to the
NAO ontology. But that's not enough because when you'll do a query like
"SELECT ?t WHERE {?t a task:Task; nao:hasTag <your_tag>.}" it will,
obviously, returns only tasks that have a direct link with the tag,
while we want to get tasks that are linked with children tags too.

Then, came another problem.
when you delete a task in gtg all subtasks are deleted. If you want to
do that in Tracker you have to get all the subtasks of the task, theirs
subtasks and finally delete all he tasks you've found.

As all softwares that features hierarchy of things will have the same
problem. I think it would be useful to solve that in Tracker.
We could add a tracker property in the ontology that says: a property
links the subject and the object in a way that, if the subject is
deleted the object must be deleted as well.
Don't know if it's clear !

Here is an example for cascading delete:
let's say we work with objects that are task:Task
we could define the property task:hasSubtask in the ontology file like
that:
> task:hasSubtask a rdf:Property ;
>    rdfs:label "hasSubtask" ;
>    rdfs:domain task:Task ;
>    rdfs:range task:Task ;
>    tracker:deleteChildwithParent true .

Obviously this is only an idea of mine, so it might be completely dumb.
But this problem is very important, so please solve it, the way you
want, or tell me how to do if I can do it right now.


Thanks,
Florent ThÃvenet