I think Waldek Jaronski wrote:
> Ernest,
>
> could I ask to have a quick look at the code below meant to print the name
> of the rule(s) which contributed to assertion of the pending need-xxx fact?
> The problem I have with this code is that it generates the following error
> after I modify a slot in a fact
>
> Error during LHS execution
> Jess reported an error in routine Node1TEQ.call
> while executing rule LHS (TEQ)
> while executing rule LHS (TECT)
> while executing (modify 9 (troubling yes)).
> Message: Error during LHS execution.
> Program text: ( modify 9 ( troubling yes ) ) at line 1.
Does Jess display a root cause exception for this? This is only part
of the error message; there should also be another bit that displays
the actual exception that occurred (i.e, the "error during LHS
execution" being referred to.)
My best guess for what's going wrong: The code looks OK except for the
cast to Defrule -- listDefrule() actually returns defqueries, too,
which are of type Defquery. The superclass of both Defrule and
Defquery is HasLHS, so you should use this class instead to be safe.
On the other hand, if you haven't defined any queries, then it has to
be something else -- the rest of the exception message should tell you
what it is. If you're catching your own exceptions, make sure you're
displaying the result of JessException.getNextException(), if it's
non-null.
>
> Here is my code:
>
> Iterator my_itr = Rete.getEngine().listDefrules();
> while (my_itr.hasNext() )
> {
> Defrule my_rule = (Defrule) my_itr.next();
> ArrayList my_al = my_rule.getNodes();
> for (int ij = 0; ij < my_al.size(); ij++)
> {
> if (my_al.get(ij) == this)
> {
> System.out.println("Rule that contributed to assertion of this
> following need-xxx fact is : " + my_rule.getName());
> }
> }
> }
>
> I insert this code at the very end of the askForBackChain() method. Do I
> make any mistake in it? Is there a better place to insert this code in this
> method perhaps?
>
> Thank you very much for your great help in advance,
> Waldek
>
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
> > Behalf Of [EMAIL PROTECTED]
> > Sent: 8 paYdziernika 2002 14:17
> > To: [EMAIL PROTECTED]
> > Subject: Re: JESS: Assertion of need-xxx facts
> >
> >
> >
> > I think Waldek Jaronski wrote:
> > > Hello,
> > >
> > > is it possible to trace the name of the rule(s) which triggered
> > assertion of
> > > a need-XXX fact? It would be very handy to know it for
> > debugging purposes
> > > when you apply backward chaining.
> > >
> >
> > Well, as you know, Jess compiles rules into a network of
> > pattern-matching nodes. It doesn't explicitly keep a list of every
> > rule that contributes to a given node. Jess does, however, keep a list
> > of all the nodes that a given rule contributed to; the
> > package-protected method "getNodes" in HasLHS returns this list. The
> > method askForBackchain in jess/Node2.java is the method that creates
> > the backward-chaining facts, so if you wanted to add this debugging
> > capability, here's what you could do:
> >
> > 1) in Node2.askForBackchain(), call Rete.getEngine().listDefrules() to get
> > an Iterator over all the rules
> >
> > 2) For each rule, call getNodes() to get the list of nodes for that
> > rule
> >
> > 3) In the list, search for "this" (the Node2 object)
> >
> > 4) If found, print a debugging message for this rule.
> >
> > This would be slow, but for debugging this shouldn't matter.
> >
> >
> > ---------------------------------------------------------
> > 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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> >
>
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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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