[rules-users] why loop fire with no-loop is true?

[Wolfgang Laun]

Both rules have no-loop, since it appears outside a rule.

But you'll have to use activation-group instead, and the 2nd
rule will then have to be modified to compute the full discount (-70)
from the initial value.

What happens is that one rule fires, modifies the fact, which will permit the
other rule to fire, even if this other one has fired before. no-loop
merely inhibits
immediate refiring of a rule that modfies the participating facts.

-W


2009/11/29 Sinboy Zhang <iamsinboy at gmail.com>
>
> i expect the result is 530,and define the "no-loop=true" in the rules ,but result is 460,why?
> --------------------------------------------------------------------------------------------------------------------------------------------------
> my java test code:
>
> package org.sample;
>
> import org.drools.KnowledgeBase;
> import org.drools.KnowledgeBaseFactory;
> import org.drools.builder.KnowledgeBuilder;
> import org.drools.builder.KnowledgeBuilderError;
> import org.drools.builder.KnowledgeBuilderErrors;
> import org.drools.builder.KnowledgeBuilderFactory;
> import org.drools.builder.ResourceType;
> import org.drools.io.ResourceFactory;
> import org.drools.logger.KnowledgeRuntimeLogger;
> import org.drools.logger.KnowledgeRuntimeLoggerFactory;
> import org.drools.runtime.StatefulKnowledgeSession;
>
> public class SalesTest {
>  public static final void main(String[] args) {
>   try {
>    // load up the knowledge base
>    KnowledgeBase kbase = readKnowledgeBase();
>    StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
>    KnowledgeRuntimeLogger logger = KnowledgeRuntimeLoggerFactory.newFileLogger(ksession, "test");
>    // go !
>    Sales message = new Sales();
>    message.setName("sinboy");
>    message.setSales(600);
>    ksession.insert(message);
>    ksession.fireAllRules();
>    //ksession.dispose();
>
>    System.out.println("updated:"+message.getName()+","+message.getSales());
>    logger.close();
>   } catch (Throwable t) {
>    t.printStackTrace();
>   }
>  }
>  private static KnowledgeBase readKnowledgeBase() throws Exception {
>   KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
>   //kbuilder.add(ResourceFactory.newClassPathResource("Sample.drl"), ResourceType.DRL);
>   kbuilder.add(ResourceFactory.newUrlResource(" http://127.0.0.1:8080/drools-guvnor/org.drools.guvnor.Guvnor/package/org.sample/LATEST"), ResourceType.PKG);
>   KnowledgeBuilderErrors errors = kbuilder.getErrors();
>   if (errors.size() > 0) {
>    for (KnowledgeBuilderError error: errors) {
>     System.err.println(error);
>    }
>    throw new IllegalArgumentException("Could not parse knowledge.");
>   }
>   KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
>   kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
>   return kbase;
>  }
> }
> the print info is:
> fired1:discount,550
> fired0:discount,530
> fired1:discount,480
> fired0:discount,460
> updated:discount,460
> ---------------------------------------------------------------------
> my java model is :
>
> package org.sample;
> import java.util.Date;
> public class Sales {
>  private String name;
>  private long sales;
>  private Date dateOfSale;
>  private boolean chocolateOnlyCustomer;
>  public String getName() {
>   return name;
>  }
>  public void setName(String name) {
>   this.name = name;
>  }
>  public long getSales() {
>   return sales;
>  }
>  public void setSales(long sales) {
>   this.sales = sales;
>  }
>  public Date getDateOfSale() {
>   return dateOfSale;
>  }
>  public void setDateOfSale(Date dateOfSale) {
>   this.dateOfSale = dateOfSale;
>  }
>  public boolean isChocolateOnlyCustomer() {
>   return chocolateOnlyCustomer;
>  }
>  public void setChocolateOnlyCustomer(boolean choclateOnlyCustomer) {
>   this.chocolateOnlyCustomer = chocolateOnlyCustomer;
>  }
> }
>
> rules:
> dialect "mvel"
> no-loop true
> rule "DiscountRule"
>    salience 9
> when
>       $fact0:Sales(s:sales>100)
> then
>       #Sales fact0=new Sales();
>       #fact0.setSales(s.getSales()-10);
>       #fact0.setName("discount");
>       #insert(fact0);
>
>       modify($fact0){setName("discount")}
>       modify($fact0){setSales(s-20)}
>       System.out.println("fired0:"+$fact0.getName()+
>                                 ","+$fact0.getSales());
> end
> rule "DiscountRule2"
>    salience 18
> when
>       $fact1:Sales(s1:sales>500)
> then
>       modify($fact1){setName("discount")}
>       modify($fact1){setSales(s1-50)}
>       System.out.println("fired1:"+$fact1.getName()+
>                                 ","+$fact1.getSales());
> end
>
>
>
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