[rules-users] "not" combined with predicate?

[Chris West]

Thanks for the feedback.

Assuming I really have a null somewhere (rather than a drools bug),
how would I go about debugging this?  Since the crash occurs in the
rule class generated at runtime, I cannot set a breakpoint to look at
which values might be null.  Any advice on this?

Thanks,
-Chris West

On 2/21/07, Edson Tirelli <tirelli at post.com> wrote:
>    Chris,
>
>    The following must work just fine:
>
> Person( girlAge : age, sex = "F" )
> not Person( boyAge : age -> ( girlAge.intValue() == boyAge.intValue() +
> 2 ), sex = 'M' )
>
>    The only reason I can see for that to fail is if age is an object
> type attribute (Integer, Double, etc) and it is set to null. Otherwise,
> it is probably a bug.
>    Bellow is not supposed to work:
>
> Person( girlAge : age, sex = "F" )
> not Person( boyAge : age, sex = 'M' )
> eval ( girlAge.intValue() == boyAge.intValue() + 2 )
>
>     The reason is because "not" means you DON'T have a Person object
> with that attributes (the boy), so you can't eval anything using "boyAge".
>
>     []s
>     Edson
>
> Chris West wrote:
>
> > Does anyone know if there is a problem using a "not" combined with a
> > predicate expression?  Drools gives me a NullPointerException
> > sometimes when evaluating my predicate.  The example from the user
> > guide is:
> >
> > Person( girlAge : age, sex = "F" )
> > Person( boyAge : age -> ( girlAge.intValue() == boyAge.intValue() + 2
> > ), sex = 'M' )
> >
> > Buy I'm trying something similar to:
> >
> > Person( girlAge : age, sex = "F" )
> > not Person( boyAge : age -> ( girlAge.intValue() == boyAge.intValue()
> > + 2 ), sex = 'M' )
> >
> > And also:
> >
> > Person( girlAge : age, sex = "F" )
> > not Person( boyAge : age, sex = 'M' )
> > eval ( girlAge.intValue() == boyAge.intValue() + 2 )
> >
> > Is there anything wrong with these?  The compiler does not have a
> > problem with the former, but does not like the latter.  I'm using
> > Drools 3.0.5.  I'm basically trying to say "there is a girl, and there
> > is not a boy whose age is 2 years less than the girl".
> >
> > Any thoughts on this would be greatly appreciated.
> >
> > Thanks,
> > -Chris West
> > _______________________________________________
> > rules-users mailing list
> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
>
>
> --
>  Edson Tirelli
>  Software Engineer - JBoss Rules Core Developer
>  Office: +55 11 3124-6000
>  Mobile: +55 11 9218-4151
>  JBoss, a division of Red Hat @ www.jboss.com
>
>
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