[rules-users] Custom EvaluatorFactory

[Mark Proctor]

Andy Mei wrote:
> Hi Edson,
>
> This is exactly what I am looking for, thanks!
>
> One comment, is it possible to expand on list of operators Drools 
> support?  Better yet, make it plugable just like EvaluatorDefinition.
Not yet, this is something we want, but our current approach to using 
antlr has limited our flexability there. We would need to rewrite the 
grammar, using an antlr-tree parser, then we should be able to have user 
definable list of operators.
>
> Correct me if I am wrong, but here are list of operators Drools support:
>   
> http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-core/src/main/java/org/drools/base/evaluators/Operator.java 
> <http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-core/src/main/java/org/drools/base/evaluators/Operator.java>
>
> Would it be possible if I could add additional operators like '+', 
> '-', '/', '%'... to any objects.  For example, I would love to allow 
> users to write syntax below, where user could subtract 3 days from the 
> current day.
>
>   $p : Position ( settlementDate < ( $TODAY - '3D' ) )
what you are using there is a return value constraint, to the engine its 
effectively a black box, and is evaluated by the chosen dialect; mvel or 
java. So if you want ot be able to do that type of arithmetic, work with 
the MVEL author to make sure its incuded in his engine.
>
> I love the project, keep up the good work.  I am negotiating with 
> management to purchase support contract from Redhat.
great :)
>
> Andy
>
> On Dec 19, 2007 6:26 PM, Edson Tirelli <tirelli at post.com 
> <mailto:tirelli at post.com>> wrote:
>
>
>        Andy,
>
>        I just added support for that in trunk (drools-4.1.0.SNAPSHOT).
>     Although trunk is a work in progress, you are welcome to try it
>     out and check if it meets your needs and provide feedback. Look
>     for the interface: org.drools.base.evaluators.EvaluatorDefinition
>     and its subclasses as examples.
>
>        []s
>        Edson
>
>     2007/12/19, Andy Mei < andy.d.mei at gmail.com
>     <mailto:andy.d.mei at gmail.com>>:
>
>         Hi,
>
>           Is there a way I could register my own custom EvaluatorFactory?
>           Drools ships with DateFactory what compares only dates, but
>         no time is included.  I would like to compare time as well.
>           I see that it would be very helpful to include capability to
>         register custom EvaluatorFactory.
>           Thanks.
>
>         Andy
>
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>
>
>
>     -- 
>       Edson Tirelli
>       JBoss Drools Core Development
>       Office: +55 11 3529-6000
>       Mobile: +55 11 9287-5646
>       JBoss, a division of Red Hat @ www.jboss.com <http://www.jboss.com>
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