This is possible with an accumulate where you code the init/action/result explicily. Perhaps not fully "out of the box" but a box that holds everything would be rather big, wouldn't it? ;-) -W 2011/11/15 Bruno Freudensprung <bruno.freudensprung(a)temis.com&gt; > ** > Hi all, > > There is something I can't express using "collect" or "accumulate" and I > would like to have your opinion. > Let's imagine I have the following types : > > # a country type > * declare Country > name : String > end > * > # a city type holding a reference to its country > * declare City > name : String > country : Country > end > * > Let's imagine I have all Country and City objects into the working memory. > I want to get the set of Countries corresponding to Cities whose name > starts with "X". > > I have the impression that I need a kind of (nonexistent right?) > "collect" syntax that would look like the "accumulate" syntax (a kind of > "anonymous" accumulate function): > > # meaning I want to collect $country objects and not City objects > $countries : HashSet() from collect (City($name matches "X.*", > $country : country)*, $country*) > > Or a home made accumulate function that builds a set of countries: > > # custom "buildset" accumulate function > $countries : HashSet() from accumulate (City($name matches "X.*", > $country : country), *buildset*($country)) > > Do you see any other (possibly out of the box) solution? > > Many thanks in advance for your answers, > Best regards, > > Bruno. > > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > > _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

** Hi Wolfgang, hi Estaban, Many thanks for your insights! I'll stick to a custom accumulate function since it is more consice than the init/action/result approach. And since I am using Drools 5.1.1, I'll create functions named collectList and collectSet to be "future proof" :-) Best regards, Bruno. Le 16/11/2011 10:34, Esteban Aliverti a écrit : You already have 2 accumulate functions to do what you need: - collectList - collectSet So, your rule will look like this: $countries : HashSet(empty == false) from accumulate (City($name matches "X.*", $country : country), collectSet($country)) Best Regards, XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Esteban Aliverti - Developer @ http://www.plugtree.com - Blog @ http://ilesteban.wordpress.com _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

** Just tested and... you are right (although they are not mentioned in the documentation)! :-). Great! Thanks a lot Esteban! Bruno. Le 16/11/2011 10:50, Esteban Aliverti a écrit : As far as I know, these 2 functions already exist in 5.1.1. Don't they? Best Regards, XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Esteban Aliverti - Developer @ http://www.plugtree.com - Blog @ http://ilesteban.wordpress.com _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users