4:02 a.m.
I am a bit surprised by your answer...
Let's consider :
rule "likes french cheese1"
when
FrenchCheese( smell == "good" )
then
System.out.println("likes french cheese1");
end
rule "likes french cheese2"
when
$person : Person ()
FrenchCheese( smell == "good" ) from $person.getLikes()
then
System.out.println("likes french cheese2");
end
These 2 rules do not behave the same way :
- First one simply does not match (with a Cheese instance inserted in WM)
- Second one throws an error (see third test in my original mail)
Chris
2007/9/27, Edson Tirelli <tirelli(a)post.com>:
Ideal IMO would be a compile time error, since getLikes() returns a
Cheese instance, but as we use MVEL to resolve the expression, I'm not 100%
sure we are able to cover all possible scenarios at compile time. I guess we
can, but need to double check that.
[]s
Edson
2007/9/27, Chris Woodrow <woodrow.chris(a)gmail.com>:
>
> Thanks.
> I was supposing so...
> Do you think test 3 should throw a ClassCastException or just not match?
> Chris
>
> 2007/9/27, Edson Tirelli < tirelli(a)post.com >:
> >
> >
> > Yes, drools is deferring the type verification until it is needed
> > (in your example, to check the constraint). May I ask you please to open a
> > JIRA... I will fix that.
> >
> > []s
> > Edson
> >
> > 2007/9/27, Chris Woodrow <woodrow.chris(a)gmail.com>:
> >
> > > I am sorry I didn't mean 'for' but 'from'.
> > > :D
> > >
> > > 2007/9/27, Chris Woodrow < woodrow.chris(a)gmail.com>:
> > > >
> > > > Hi,
> > > > I recently find out a few issues using for, and I wanted to share
> > > > it with you. I made a simple exemple to illustrate my purpose.
> > > >
> > > > My classes are (I did not represent accessors & constructors):
> > > >
> > > > public class Cheese {
> > > > protected String name;
> > > > }
> > > >
> > > > public class FrenchCheese extends Cheese{
> > > > private String smell;
> > > > }
> > > >
> > > > public class Person {
> > > > private Cheese likes;
> > > > }
> > > >
> > > > Here is my rule set :
> > > >
> > > > package rules
> > > >
> > > > rule "likes cheese"
> > > > when
> > > > $person : Person ()
> > > > Cheese( ) from $person.getLikes()
> > > > then
> > > > System.out.println ("likes cheese");
> > > > end
> > > >
> > > >
> > > > rule "likes french cheese"
> > > > when
> > > > $person : Person ()
> > > > FrenchCheese( ) from $person.getLikes()
> > > > then
> > > > System.out.println ("likes french cheese");
> > > > end
> > > >
> > > > First test :
> > > > Cheese cheese = new FrenchCheese("good",
"camembert");
> > > > Person person = new Person();
> > > > person.setLikes(cheese);
> > > >
> > > > Output :
> > > > likes french cheese
> > > > likes cheese
> > > >
> > > > Wich is expected...
> > > >
> > > > Second test :
> > > > Cheese cheese = new Cheese();
> > > > Person person = new Person();
> > > > person.setLikes(cheese);
> > > >
> > > > Output :
> > > > likes french cheese
> > > > likes cheese
> > > >
> > > > That's the first strange thing. As far as I am concerned, rule
> > > > "likes french cheese" should not match (since a Cheese is
not a
> > > > FrenchCheese).
> > > >
> > > > I made a change to the second rule :
> > > > rule "likes french cheese"
> > > > when
> > > > $person : Person ()
> > > > FrenchCheese( smell == "good" ) from
$person.getLikes()
> > > > then
> > > > System.out.println("likes french cheese");
> > > > end
> > > >
> > > > Third test :
> > > > Cheese cheese = new Cheese();
> > > > Person person = new Person();
> > > > person.setLikes(cheese);
> > > >
> > > > output :
> > > > It throwed an exception : Exception in thread "main"
> > > > java.lang.ClassCastException: rules.Cheese
> > > > I am not saying the ClassCastException is not to expect in such a
> > > > case but I think I would simply expect it not to match (as far as a
Cheese
> > > > is not a FrenchCheese).
> > > >
> > > > Chris
> > > >
> > >
> > >
> > > _______________________________________________
> > > rules-users mailing list
> > > rules-users(a)lists.jboss.org
> > > https://lists.jboss.org/mailman/listinfo/rules-users
> > >
> > >
> >
> >
> > --
> > Edson Tirelli
> > Software Engineer - JBoss Rules Core Developer
> > Office: +55 11 3529-6000
> > Mobile: +55 11 9287-5646
> > JBoss, a division of Red Hat @ www.jboss.com
> > _______________________________________________
> > rules-users mailing list
> > rules-users(a)lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
> >
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
--
Edson Tirelli
Software Engineer - JBoss Rules Core Developer
Office: +55 11 3529-6000
Mobile: +55 11 9287-5646
JBoss, a division of Red Hat @ www.jboss.com
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