Thanks a lot Edson, you have been a big help.

And yeah I figured as much regarding the Eclipse IDE. Will try the approach you suggested.

Again thanks a lot.

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Edson Tirelli
Sent: 15 July 2009 14:47
To: Rules Users List
Subject: Re: [rules-users] Getting hold of the Evaluator Registry

   Hmm, strange, I could swear those operators supported strings... but looking at the code, it is not there... :( anyway, patch welcome... ;)

   Regarding your questions:

1. Yes, in this case you could simply override the operators adding the support to Strings.

2. In Drools, any configuration can be done in one of 3 ways: system property, configuration file or API. They all work the same, the only difference being the Eclipse IDE: the eclipse IDE only picks up configurations on the configuration file. So, if you configure a custom operator using the API, your application will run just fine, BUT the eclipse DRL editor will show an error because it does not "run your API calls before parsing/compiling the content of the DRL editor". So, the best way to do it when working with the IDE is simply write configurations like this in the following file in the classpath of your eclipse project:

META-INF/drools.packagebuilder.conf

3. Yes, it will, but that is the old API. The recommended way for Drools 5 is to use the public APIs in the drools-api module.

   []s
   Edson

2009/7/15 Asif Iqbal <Asif.Iqbal@infor.com>

Edson,

Thanks for your replies they have really helped.

1) I am still not sure about creating a new operator, since the ‘>=’ operator already exists it just does not cater for strings, which I want to add. So would creating a new operator cause the existing one to be overrriden when added to the registry?

2) Having looked at the examples and tests you emailed, I am still unsure how to actually wire in the changes, say for example I have replaced the existing ‘>=’ evaluator or created a new evaluator so that ‘>=’ now handles strings. When writing rules will the engine pick this up?.. or do I need to create a new jar by building?.. or do I need to update a configuration file?... im just not sure…

3) Wouldn’t the following also add the evaluator definition by replacing the existing one..

PackageBuilderConfiguration pkgb = new PackageBuilderConfiguration();

pkgb.getEvaluatorRegistry().addEvaluatorDefinition(new ComparableEvaluatorsDefinition());

PackageBuilder builder = new PackageBuilder(pkgb);

builder.addPackageFromDrl(source);

Package pkg = builder.getPackage();

// Add the package to a rulebase (deploy the rule package).

rules = RuleBaseFactory.newRuleBase();

rules.addPackage(pkg);

Thanks for your help…

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Edson Tirelli
Sent: 14 July 2009 23:05
To: Rules Users List
Subject: Re: [rules-users] Getting hold of the Evaluator Registry

   I am working in one example of drools features where I implement a custom evaluator here:

http://anonsvn.jboss.org/repos/labs/labs/jbossrules/contrib/lotrc/src/main/java/org/drools/examples/lotrc/evaluators/IsAdjacentToEvaluatorDefinition.java

   I use the configuration file instead of API in the example:

http://anonsvn.jboss.org/repos/labs/labs/jbossrules/contrib/lotrc/src/main/resources/META-INF/drools.packagebuilder.conf

   []s
   Edson

2009/7/14 Edson Tirelli <tirelli@post.com>

   Asif,

   My recommendation is create a new operator for you instead of overriding existing ones. Although if you really want to replace the existing ones, setting the property or calling the API to register a new operator will override the default.

   See:

http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-compiler/src/test/java/org/drools/builder/KnowledgeBuilderConfigurationTest.java

   Test method:

testEvaluatorConfiguration()

   []s
   Edson

2009/7/14 Asif Iqbal <Asif.Iqbal@infor.com>

Hi,

What I need to do is modify one of the evaluator classes specifically ‘<=’, so that it can handle strings. Now I know I need to create a class similar to ComparableEvaluatorDefinition. But what I want to do is replace the existing one in the evaluator registry with my implementation which will include the additional String capability.

From my understanding that should be all that is required. Unless im missing something… now all I need to know is how do I get hold of the evaluator registry?

Cheers

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Edson Tirelli
JBoss Drools Core Development
JBoss by Red Hat @ www.jboss.com

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