[rules-users] Getting hold of the Evaluator Registry

[Edson Tirelli]

   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 at 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 at lists.jboss.org [mailto:
> rules-users-bounces at 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 at 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 at 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
>
>
>
> I
>
>
>
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>
>
>
>
> --
>  Edson Tirelli
>  JBoss Drools Core Development
>  JBoss by Red Hat @ www.jboss.com
>
>
>
>
> --
>  Edson Tirelli
>  JBoss Drools Core Development
>  JBoss by Red Hat @ www.jboss.com
>
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>
>


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