[rules-dev] SumIntegerAccumulateFunction not possible?

[Geoffrey De Smet]

http://jira.jboss.com/jira/browse/JBRULES-1074

Is there any accumulate testcase I could copy paste to create a testcase 
for this issue?

With kind regards,
Geoffrey De Smet


Geoffrey De Smet wrote:
> 
> 
> 
> Edson Tirelli wrote:
>>
>>    Hey Geoffrey,
>>
>>    Lets talk about short term and long term.
>>
>> * Long term: we may need to find a way to support primitives. Right 
>> now, primitives are wrapped to simplify custom function developments.
> 
> That would be nice indeed. Or at least support all their wrapper types.
> Then you can leave it to JIT to optimize it at runtime if performance is 
> needed.
> 
>>
>> * Short term: knowing that all primitives are wrapped, we always 
>> recommend you to use Number instead of the concrete wrapper classes 
>> implementations.
>>
>>      public void accumulate(Object context,
>>                             Object value) {
>>          SumIntegerAccumulateFunction.SumData data = 
>> (SumIntegerAccumulateFunction.SumData) context;
>>          data.total += ((Number) value).intValue();
>>      }
> 
> I 'll probably do a workaround like this for now, but it's a bit slower.
> The big advantage will be switching from double to long. That's like 
> 3-5% last I did that switch.
> Nevertheless switching from long to int might be noticeable too. I 'd 
> like to test it in either case :)
> 
> 
>>
>>     Now, the explanation: to add flexibility to the users writing 
>> rules with your function, we support expressions that are MVEL 
>> evaluated and the result is sent to the function implementation. So, 
>> in your example, if the user wanted to sum the double of the 
>> distances, he could write instead:
> 
> I am using MVEL? I though I wasn't as I use eval(...) etc?
> 
>>
>>      $totalDistance : Integer() from accumulate(
>>         Hop($distance : distance),
>>         sumInteger( $distance * 2 )
>>      );
>>
>>     So, what goes between () is really any valid mvel expression and 
>> as such, MVEL decides what is the wrapper class to return the result. 
>> Apparently, it is returning a Long for integer type numbers.
> 
> Maybe drools could use some sort of overloading of the accumulate function?
> 
> A)
> sum(int), sum(long), sum(double), ...
> Then drools declares that they should always use the same type in one 
> usage of sum in a rule?
> Then if they want to mix double with long, they can do sum((double) 
> $myDouble)?
> 
> B)
> Or drools could look at the return type (being Integer in the above 
> case), but that makes it out of sync with the java spec.
> 
>>
>>     Being brief, it is flexible, powerful and expressive, but it may 
>> require some refactorings in the future to improve performance, if it 
>> becomes an issue.
> 
> You know my use case. Performance is everything :)
> I can now beat the nl12 TTP record of 2002 in 2 hours.
> Once I boost up the performance/scalability some more, I 'll let it run 
> for a week or more and hope to beat today's records.
> 
>>
>>     Hope it helps.
> Help is always welcome :)
>>
>>        Edson
> 
> With kind regards,
> Geoffrey De Smet
>>
>>
>> 2007/8/11, Geoffrey De Smet <ge0ffrey.spam at gmail.com 
>> <mailto:ge0ffrey.spam at gmail.com>>:
>>
>>     It looks like the value objects of the accumulate framework are 
>> always
>>     Long's - even when they are Integers?
>>
>>
>>     Caused by: java.lang.ClassCastException: java.lang.Long cannot be 
>> cast
>>     to java.lang.Integer
>>             at
>>     
>> org.drools.base.accumulators.SumIntegerAccumulateFunction.accumulate(SumIntegerAccumulateFunction.java:36) 
>>
>>             at
>>     
>> org.drools.base.accumulators.JavaAccumulatorFunctionExecutor.accumulate(JavaAccumulatorFunctionExecutor.java 
>>
>>     :79)
>>
>>
>>
>>     Here's the piece of code:
>>
>>          public void accumulate(Object context,
>>                                 Object value) {
>>              SumIntegerAccumulateFunction.SumData data =
>>     (SumIntegerAccumulateFunction.SumData ) context;
>>              data.total += ((Integer) value).intValue(); // breaks
>>          }
>>
>>
>>     Here's the drl:
>>
>>        when
>>          $totalDistance : Integer() from accumulate(
>>             Hop($distance : distance),
>>             sumInteger($distance)
>>          );
>>
>>
>>     Here's the Hop object:
>>
>>          public int getDistance() {
>>              ...
>>          }
>>
>>     Look ma, no longs :) Still a ClassCastException on them though.
>>     I must be missing something really obvious?
>>
>>     --
>>     With kind regards,
>>     Geoffrey De Smet
>>
>>     _______________________________________________
>>     rules-dev mailing list
>>     rules-dev at lists.jboss.org <mailto:rules-dev at lists.jboss.org>
>>     https://lists.jboss.org/mailman/listinfo/rules-dev
>>
>>
>>
>>
>> -- 
>>   Edson Tirelli
>>   Software Engineer - JBoss Rules Core Developer
>>   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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