[rules-users] counting facts of a kind

[Edson Tirelli]

    Wolfgang,

    The requirement for serializable classes even when not using persistence
was a "mistake" made several versions ago and I believed it was fixed. What
version of Drools are you using? If that is trunk, we need to fix it.

    Anyway, workaround: for count(), you can simply write "count(1)" instead
of using the actual variable, anyway (yes, you can see requiring
serializable there was dumb). :)

    Edson

2010/8/23 Wolfgang Laun <wolfgang.laun at gmail.com>

> No, not knowingly :-) I'm using the simplest possible setup for
> KnowledgeBase, KnowledgeBuilder, StatefulKnowledgeSession.
>
> Why should accumulate/count effect persistence?
>
> -W
>
>
> 2010/8/23 Swindells, Thomas <TSwindells at nds.com>
>
>>  You’ve probably configured your system to be using persistence?
>>
>> In which case what you are persisting needs to be serializable so that it
>> can be persisted
>>
>>
>>
>> Thomas
>>
>>
>>
>> *From:* rules-users-bounces at lists.jboss.org [mailto:
>> rules-users-bounces at lists.jboss.org] *On Behalf Of *Wolfgang Laun
>> *Sent:* 23 August 2010 12:17
>> *To:* Rules Users List
>> *Subject:* [rules-users] counting facts of a kind
>>
>>
>>
>> As simple as it gets:
>>
>> rule countHigh
>> when
>>     $n : Number() from accumulate ( $sgc : StartGoalConn() count( $sgc ) )
>> then
>>     System.out.println( "plain routes: " + $n );
>> end
>>
>> And yet, it fails:
>>
>> Exception in thread "main" org.drools.RuntimeDroolsException:
>> java.lang.ClassCastException: rss.ixl.route.TrainStartGoalConn cannot be
>> cast to java.io.Serializable
>>
>> Sure, adding "implements Serializable" to StartGoalConn fixes this. But
>> why is this necessary?
>>
>> FYI, StartGoalConn is abstract superclass of TrainStartGoalConn - just in
>> case this has some bearing on this issue.
>>
>> Best
>> -W
>>
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-- 
  Edson Tirelli
  JBoss Drools Core Development
  JBoss by Red Hat @ www.jboss.com
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