On Feb 18, 2012, at 12:35 AM, Andy Seaborne wrote:
> Another suggestion: put a marker pattern into the query and then you can find
> it again.
>
> Put in the triple
> <tq:holger> <tq:holger> <tq:holger> .
Thanks, Andy, for looking into this. Unfortunately those queries are not
written by myself, and they might be anything. So I cannot rely on a marker
triple. It's basically a feature of the SPIN framework in which rules and
constraints can be attached to classes. The variable ?this is then supposed to
be (pre) bound to all instances of those classes. My current solution was to
insert this clause that iterates over all instances where ?SOME_TYPE is
pre-bound to the class using initial bindings. This works fine in most cases,
but if some query only uses a function call (and BIND) then the ?this variable
may not already be bound and the function call fails.
Is there perhaps a way to control the table unit (if that's always there), so
that this could instead be a BGP? Maybe I could pre-process the ops but I don't
understand the algebra mechanism well enough on a reliable pattern on what
replacement I would need to do. A syntactic insertion based on { sounds
brittle, esp since there are things like GRAPH etc that switch to a completely
different query graph.
Maybe I need to really do the iteration "outside" for certain rules and
constraints if there is no simple place for a ?this binding BGP. This will be
slower but at least correct. Do you have any other ideas?
Thanks a lot
Holger
