Ernest,
thanks for the response. I had thought of using executeCommand but reasoned that
it was actually more expensive than my rule because each time it is executed (which
may be quite a number of times) I pay the penalty of having to parse and compile the
command. Just of of curiosity (and because I'm too lazy to check it out) do you have
a feel for which would win in terms of speed -- compiling the string each time or
executing the rule ??
Anyway your second approach definitely rules (arghh) and I should have thought of it.
Generally speaking would it be useful to bring definstace out as a Rete method (or
however your new factoring is going to look)? I can assert from within rete --
wouldn't it seem that definstance shares the same position in the scheme of things
(especially as I find one of the joys of Jess to be the Bean<->(shadow)Fact duality)
?
Tnx
Alanl
[EMAIL PROTECTED] wrote:
> You're right that there's no direct method you can call to create a
> definstance from Java, although the same is true of many other Jess
> functions. Instead you can either do something like what you've done
> below, or create and use a Funcall object.
>
> First, an improvement on the scheme below that doesn't require a rule!
>
> rete.store("FOO", obj);
> rete.executeCommand("(definstance class-name (fetch FOO) dynamic)");
>
> Second, the Funcall approach. First, build the funcall:
>
> Funcall f = new Funcall("definstance", rete);
> f.add(new Value("class-name", RU.ATOM));
> f.add(new Value(obj));
> f.add(new Value("dynamic", RU.ATOM));
>
> Then you can execute it once:
>
> f.execute(rete.getGlobalContext());
>
> Then you can reuse it as many times as necessary:
>
> f.set(newObj, 2); // replace obj with newObj
> f.execute(rete.getGlobalContext());
>
> Wrap these last two lines in a method called definstance(Object)
> someplace, make f a member of the method's class,and you're all set.
>
> I think Alan Littleford wrote:
> > Forgive me if I've missed something obvious but:
> >
> > I cannot see a way of 'Definstancing' from within a Userfunction --
> > the Definstance functionality within Jess seems private. Is this by
> > design, or am I just mssing something very obvious? As it is now I
> > simply assert a fact 'foo(OBJECT ?obj)' from my user function ( where
> > ?obj is the address of my Bean created within my user function) and then
> > I have a rule within Jess along the lines of :
> >
> > (defrule defitup
> > ?f<-(foo (OBJECT ?obj))
> > =>
> > (definstance <?class-name> ?obj dynamic)
> > (retract ?f) ;; don't need it any more
> > )
> >
> > which although it works fine seems to be laborious at best. BTW I'm
> > using Jess 5.1 (still intending to move to Jess 6 at some point!)
> >
> > Thanks to anyone who can shed light on this
> >
> > Alanl
> >
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>
> ---------------------------------------------------------
> Ernest Friedman-Hill
> Distributed Systems Research Phone: (925) 294-2154
> Sandia National Labs FAX: (925) 294-2234
> Org. 8920, MS 9012 [EMAIL PROTECTED]
> PO Box 969 http://herzberg.ca.sandia.gov
> Livermore, CA 94550
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