In forward chaining engines, "or" is just syntax sugar to automatically generate multiple rules (one for each logical branch) that would trigger the exact same consequence action. If you need different consequence actions, you need to write different rules. As a side effect of this, all variables used in the consequence must be defined in all logical branches.
Edson
2011/2/3
<thomas.polzin@gmail.com>
Hi there
Assume we have a rule like this:
when
$a : A(a==1)
or
($b : B(b==1) and $c : C(c==1))
then
do($a)
do($b)
do($c)
end
Assuming also, that for some reason I do not want to split this rule into two.
Then, I get a NullPointer exception because either $a or $b and $c are not defined.
Is there a way to catch or check for this.
Thanks so much for any help
Thomas
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Edson Tirelli
JBoss Drools Core Development
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