[jboss-jira] [JBoss JIRA] Commented: (JBRULES-577) Please add "contained by" syntax for constraints

[Mark Proctor (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBRULES-577?page=comments#action_12348236 ] 
            
Mark Proctor commented on JBRULES-577:
--------------------------------------

If its not time constant then then it belongs in an eval - we won't be changing that. We'll look into an 'in' operator, we had plans to use an 'in' operator with a static list of values, maybe we can extend that.

> Please add "contained by" syntax for constraints
> ------------------------------------------------
>
>                 Key: JBRULES-577
>                 URL: http://jira.jboss.com/jira/browse/JBRULES-577
>             Project: JBoss Rules
>          Issue Type: Feature Request
>      Security Level: Public(Everyone can see) 
>          Components: Drl Parser/Builder
>            Reporter: Dirk Bergstrom
>         Assigned To: Edson Tirelli
>
> I'd like to be able to write a constraint to determine if a field's value is a member of some collection.  This is the inverse of the "contains" keyword.  The proposed syntax is:
> [bindingVar :] <fieldName> in <someCollection>
> (I'm not picky about the keyword, other possibilities are "containedBy" or "memberOf", but "in" is a single word)
> Use case:
> I have a container class with a field that exposes a collection of record
> numbers.  In the working memory, I have a bunch of record objects, and one
> container object.  I want to write a rule that fires when it encounters a
> container that has records matching some criteria:
> when
>   Container( $recordNums : records )
>   Record( number in $recordNums, otherField == "somevalue" )
> then
>   doStuff();
> The current workaround is:
>   Record( num : number -> ( $recordNums.contains(num) )  )
> Which is problematic, as the predicate may not be time-constant.

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