Your goal and the presented code aren't clear to me. The consequence (after then) contains calls to static/class methods (Box.setX()) which isn't going to change anything in your fact object. The call b.setX() might change your object, but this depends on what the class method Box.getX() returns. Assuming Drools 5, a typical consequence would look like    b: Box(...) then    modify( b ){       setX( ... )    } end -W On Sat, Aug 8, 2009 at 1:48 AM, sonia <robotnic+drools(a)gmail.com&gt; wrote: > > Hello > > I want to achieve this: > box1.setX(0) > box2.setX(box1.size()); > box2.setX(box1.size + box2.size) > ... > > I want to do it with rules, and would like to know what's the best > method of initializing (or any other operation with varying data) a > group of objects > > rule "init box" >  when >   b : Box( x == -1) >  then >   b.setX(Box.getX()); >   Box.setX( Box.getX() + b.size); > end > > This does not work. > A single box object is matched several times instead of different box > objects. > What is happening? how come a single box object is matched several > times? Why doesnt drools choose other instances of box? > > What do I need to do to initialize all boxes, once for every box? > > Thank you. > > -- > robosonia > _______________________________________________ > 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