7:35 a.m.
Chris
Version 3.0.x prevents by default a single fact from matching multiple
patterns. For a couple of reasons we had to change the default in 4.0 to
allow a single fact to match multiple patterns. If you don't want this to
happen, you can use one of the following approaches:
* Change the behavior for the whole rulebase. You can do that by either
setting a system property ("drools.removeIdentities=true") or creating a
RuleBaseConfiguration instance:
RuleBaseConfiguration conf = new RuleBaseConfiguration();
conf.setRemoveIdentities( true );
RuleBase rulebase = new ReteooRuleBase( conf );
* Alternativelly, you can manually add a constraint to avoid the behavior
for specific rules, using the "this" keyword.
rule "TwoCheeses"
when
$cheese1 : Cheese();
$cheese2 : Cheese( this != $cheese1 );
then
System.out.println($cheese1);
System.out.println($cheese2);
System.out.println("TwoCheeses");
end
We will add such information to the documentation, but the above shall
give you the idea.
Hope it helps,
Edson
2007/5/15, Chris Woodrow <woodrow.chris(a)gmail.com>:
Hi everyone,
I am new to this mailing list, I've had a quick look at archives and
didn't find anything ont this subject but sorry if this has allready been
underlined.
Here is my problem, while I was doing some test on v3.0.6, 4.0.0 came out,
so I started to migrate on the new version. Then I found out an unexpecteed
behavior on the 4.0.0.
I have been compiling both with Java 5 and running whith Java 1.5.0_11.
And I used versions with dependencies on both tests.
I have made an exemple for you to make it as clear as possible, here is
the rule :
---------------------------------------------------------------------------------------
package rules
rule "TwoCheeses"
when
$cheese1 : Cheese();
$cheese2 : Cheese();
then
System.out.println($cheese1);
System.out.println($cheese2);
System.out.println("TwoCheeses");
end
---------------------------------------------------------------------------------------
When I run it on V3.0.6, with this code :
---------------------------------------------------------------------------------------
package rules;
import java.io.InputStreamReader;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.WorkingMemory;
import org.drools.compiler.PackageBuilder;
public class Cheese {
public static void main(String[] args) throws Exception{
PackageBuilder builder = new PackageBuilder();
builder.addPackageFromDrl(new InputStreamReader(
Cheese.class.getResourceAsStream ("rule.drl")));
RuleBase ruleBase = RuleBaseFactory.newRuleBase();
ruleBase.addPackage(builder.getPackage());
WorkingMemory workingMemory = ruleBase.newWorkingMemory ();
Cheese cheese = new Cheese();
workingMemory.assertObject(cheese);
workingMemory.fireAllRules();
}
}
---------------------------------------------------------------------------------------
The rule doesn't fire, which is normal AMHA since only one Cheese object
is asserted to the WM
When I run it on V4.0.0, whith this code :
---------------------------------------------------------------------------------------
package rules;
import java.io.InputStreamReader;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.StatefulSession;
import org.drools.compiler.PackageBuilder;
public class Cheese {
public static void main(String[] args) throws Exception{
PackageBuilder builder = new PackageBuilder();
builder.addPackageFromDrl(new InputStreamReader(
Cheese.class.getResourceAsStream ("rule.drl")));
RuleBase ruleBase = RuleBaseFactory.newRuleBase();
ruleBase.addPackage(builder.getPackage());
StatefulSession statefulSession = ruleBase.newStatefulSession();
Cheese cheese = new Cheese();
statefulSession.assertObject(cheese);
statefulSession.fireAllRules();
}
}
---------------------------------------------------------------------------------------
Now the rule fires and $cheese1 $cheese2 have the same reference.
I have been searching in all docs, this modification of behavior doesn't
seem to be expected, has anyone noticed this?
Thanks for your help.
Chris
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Edson Tirelli
Software Engineer - JBoss Rules Core Developer
Office: +55 11 3529-6000
Mobile: +55 11 9287-5646
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