The short answer: yes, this is how it works. Your function will be
called both to check for new matches, and to confirm old ones, and
Jess may or may not memoize the results so that your function may not
be called when you think it might. You can't use a method whose return
value varies over time this way, or your system will quickly become
inconsistent, for the same reasons that a Java Comparator with a time-
varying return value could not be used to sort an array.
On Apr 24, 2009, at 7:16 AM, bohlken wrote:
Hello all,
I have defined a rule with the shadow facts TimePoint like this:
(defrule myRule1
(TimePoint (name ?name1)(OBJECT ?tp1-obj))
(TimePoint (name ?name2)(OBJECT ?tp2-obj))
(test (call ?*myTest* check ?tp1-obj ?tp2-obj))
=>
...)
*myTest* is a JAVA Object with a check function.
Now, lets say the rule will be activated (the result of check is
true).
In my application it can happen, that the result of the check function
becomes false, independend(!) of the facts in the rule.
Now, if a fact changes, the following happens:
- the check function is called with the OLD values - before the fact
has
changed(!) -, if the result is true, then the rule is deactivated,
the fact
is changed, the check function is called again, and if true, the
rule is
activated again
- if the check function with the OLD values is false, then the rule
will NOT
be deactivated. The fact is changed, the check function is called
again. It
can again be false and the rule will NOT be deactivated.
Is this a bug or a feature?
Thanks,
Wilfried
Wilfried Bohlken
Arbeitsbereich Kognitive Systeme
FB Informatik
Universitaet Hamburg
Vogt-Koelln-Str. 30
22527 Hamburg
Germany
Tel.: +49-40-42883-2577
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Ernest Friedman-Hill
Informatics & Decision Sciences Phone: (925) 294-2154
Sandia National Labs
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Livermore, CA 94550 http://www.jessrules.com
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