[rules-users] insertLogical and modifyRetract

[Gras, Patrick]

Hello,
 
If you can change the code for CreatedFact and let it have a reference to UserFact and change the rule to:
 
rule "fact = 1"
    when
        $f : UserFact(fact1 == 1);
    then 
          insertLogical(new CreatedFact($f));         
end

you will also have to overide equals and hashcode for CreatedFact so that several CreatedFacts referencing the same UserFact are considered equal...
 
But with this solution CreatedFact will always be up to date with the value of UserFact even without firing the rules and maybe it's not what you want...
 
-Patrick

-----Message d'origine-----
De : rules-users-bounces at lists.jboss.org [mailto:rules-users-bounces at lists.jboss.org]De la part de tim tim
Envoyé : mardi, 7. octobre 2008 16:53
À : rules-users at lists.jboss.org
Objet : [rules-users] insertLogical and modifyRetract


Hello,

I am a bit confused about how insertLogical() supposed to work in drools 5.

when i have a rule such as:

rule "fact = 1"
    when
        $f : UserFact(fact1 == 1);
    then 
          insertLogical(new CreatedFact($f.getFact2()));         
end

now i change $f in such a way, that the rule will fire again.
via 

// build first version
UserFact f = new UserFact();
f.setFact1(1);
f.setFact2(1);

memory.insert(f);
memory.fireAllRules(); // <- Rule fires once

// now i change the memory and fire the rules again

memory.modifyRetract(f) ;
f.setFact2(100); // <- changing $f, but leaving fact1 as it is.
memory.modifyInsert(f);

memory.fireAllRules();  // <- Rule fires again

now the rule should fire again, which it does.
but i end up with two CreatedFact instances in the workingMemory..
one with the old OtherFact value 1, and one with the new value, 100

but i want only the second instance. the one created first is not valid any more.
i could write an extra rule for retracting the first CreatedFact-fact, but then i would have
a very tight coupling of the two rules.
 
is there a better way?
it seems odd to me, that a consequence of a rule stays in memory, when there is
a more current version of the rule evocation with the _same_ facts in the precondition
and a different consequence.

thanks in advance, tim



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