<br> Krishna,<br><br> "this" is a special field that always refers to the fact itself, instead of an attribute. Your use of "this" is fine.<br> == used as a top level constraint evaluator always calls for the equals() method on the object in question, or the appropriate comparator when dealing with primitives.<br>
<br> []s<br> Edson<br><br><div><span class="gmail_quote">2008/1/31, Krishna Satya <<a href="mailto:krishna.ksatya@gmail.com">krishna.ksatya@gmail.com</a>>:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Greetings.<br>I am trying to find the correct approach to defining and using Java5 Enum's in Drools constraints.<br><br><b>Psudo code:</b><br>Class RuleRequest {<br> ... other attributes ...<br> // RequestType is an enum type.<br>
RequestType type ;<br><br> public RequestType getRequestType() {<br> return type;<br> }<br>}<br><br>public enum RequestType {<br> INTERNAL("internal"), EXTERNAL("external");<br>
}<br><br><b>Drools Rule:</b><br># 1st Constraint - I could have listed the type in the constraint for RuleRequest but say I want that to be in a separate constraint<br># 2nd Constraint - on the nested RequestType enum<br>
<b>req: RuleRequest(..some match not based on the RequestType but other attributes of RuleRequest...)<br>type: RequestType( ??? == RequestType.INTERNAL ) from req.requestType<br></b><br>What should be plugged in ??? to be able to match the requestType. Interestingly, if I say <br>
<b>type: RequestType( this == RequestType.INTERNAL ) from req.requestType </b>when the ruleRequest has an RequestType of INTERNAL, the matching works. But I do not see any examples/reference in the Drools documentation on the usage of "this" in constraints. I saw a posting from Edson T. using this which is why I tried it in the first place.<br>
<br><b>Question<br></b>- What is the expectation for the Enum. Should it have methods (getters) that return the Enum type itself or methods that return the strigified value of the Enum?<br>- What is syntax and usage practices for the usage of the "this" keyword<br>
- What really happens when the Drools engine does the == comparison on Enum's. Does it convert to the string value of the enum and then compare that or is there something else in play. <br><br>I hope I have asked valid questions as I see many questions relating to Enum but maybe a definitive/suggested approach and explanation from the drools dream team may serve as a good reference on this subject.<br>
<br>Thanks.<br><span class="sg">- Krishna<br><br><br><br><br><br>
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<br clear="all"><br>-- <br> Edson Tirelli<br> JBoss Drools Core Development<br> Office: +55 11 3529-6000<br> Mobile: +55 11 9287-5646<br> JBoss, a division of Red Hat @ <a href="http://www.jboss.com">www.jboss.com</a>