Hi,
Don't know if this is what you are looking for, but in Jess, null is
represented as nil (inherited from CLIPS).
http://www.jessrules.com/jess/docs/71/basics.html
Try this out:
(deftemplate foo
(slot bar)
(slot qwe) )
(defrule r
?f <- (foo (qwe nil))
=>
(printout t "Got a null slot: " ?f.bar crlf) )
(assert (foo (bar 1)))
(assert (foo (bar 2) (qwe null)))
(run)
Cheers,
Henrique
David Coyle wrote:
> Hello:
>
> I'm working with objects that have numerous relationships to others.
>
> There are a number of times where I need to simply check whether a
> particular relationship is or is not null, without caring about the
> actual destination object itself.
>
> I haven't found an appropriate function: does one exist, or is there
> a standard approach to determining null?
>
> thanks,
>
> -dave-
>
>
> David Coyle PhD
> Lead Web Application Architect
> m: 919.454.7770
> www.livescribe.com
> ----------------------------------
> LiveScribe, Inc.
> 7677 Oakport St. 12th Floor
> Oakland, CA 94621
>
>
>
>
>
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DEI/FEUP
Rua Dr. Roberto Frias | 4200-465 Porto
PORTUGAL
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