[rules-users] How to use a result of custom defined function in WHEN part?

[Wolfgang Laun]

On 18 December 2010 18:25, AleBu <aleboo at gmail.com> wrote:

>
> Hi,
> [offtopic]
> Thanks for quick response! It is always nice when project has an active and
> friendly community. This is a sign of healthy project itself :)
> [/offtopic]
> My function was returning a collection.


If it returns a Collection<Tuple> you should be able to use

when
       Something( $letters: collectionOfLetters )
       Tuple( $letter: first, $count: second > 1 ) from createCardinality(
$letters )
then
       System.out.println( "Letter "+letter+" is duplicated "+$count+"
times" )
end

"from collect" generates a Collection<X> from individial X's; from
<Collection-expression> inspects elements coming from a collection.

Please note that better help can be obtained by showing all of the relevant
code and the error messages.
-W


> It seems that I made an error in
> import of the function. I had some debug, info, etc static methods in the
> class and they were imported with import function ...* and it worked, so I
> expected that adding public static createCountMap(...) into the same class
> will solve it too, but somehow I needed to declare it explicitly.
> Also, having the same code in Drools file in function declaration is not
> working when I use java 5 syntax, so I just rewrote it with java 1.4 syntax
> and it works fine too. If there is such a restriction, then it for sure
> missed in official documentation
>
> http://downloads.jboss.com/drools/docs/5.1.1.34858.FINAL/drools-expert/html/ch04.html#d0e3200
> .
> So, that were all my problems were :).
> Thanks again for response!
> I also can see another approach for solving the problem in the thread, so I
> will play with it too - it looks interesting for me. Thinking in the
> declarative drools like style requires some brain restructuring. It is like
> moving from imperative to functional programming. And speaking of
> functional
> approach - It reminds me about Scala and question here is:
> Can Scala be used as one of the dialects in the future? Are there any plans
> or thinkings or wishes in the "wish-list" for it? :}
>
> --
> View this message in context:
> http://drools-java-rules-engine.46999.n3.nabble.com/How-to-use-a-result-of-custom-defined-function-in-WHEN-part-tp2110515p2111854.html
> Sent from the Drools - User mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20101218/920ebfcf/attachment.html