Re: [rules-users] Problem passing objects to a method via the eval statement

The 'or' must be used for classes of the same type.

Mark Joshua Undesser wrote: > I am curious if anyone else has run into this problem.....It seems > like there > is something wrong in the Drools Logic....My issue can be very easily be > recreated in about 5 minutes.... > > >From eclipse I set up a new drools project. Where DroolTest.java is > defined I create 4 new classes, ClassA, ClassB extends ClassA, ClassC > extends ClassA, and ClassD. > > Each of these classes has a default constructor that does nothing, > there are > no attributes or anything in these classes just to make the example > simple > to reproduce. Ie ClassA looks like this.... > > > > package com.sample; > > public class ClassA { > > public ClassA() { > } > } > > > > Now within the DroolsTest.java source code at line 29 (ie right after > the > workingMemory.insert( message ) method call I added 4 more lines which > creates and inserts two objects... > > ClassB classB = new ClassB(); > ClassD classD = new ClassD(); > workingMemory.insert( classB ); > workingMemory.insert( classD ); > > and then the next line would be the > workingMemory.fireAllRules(); as normal. > > > Then in the sample.drl file I add the following rule and functions > > 1 rule "Test" > 2 when > 3 > 4 $classA : ClassA() > 5 $classD : ClassD() > 6 > 7 (or > 8 $classB : ClassB(eval($classB == $classA)) > 9 $classC : ClassC(eval($classC == $classA)) > 10 ) > 11 > 12 eval(retB($classA, $classD)) > 13 > 14 then > 15 System.out.println("\n\n<<FIRE RULE>>TEST"); > 16 end > 17 > 18 function boolean retA(Object obj) { > 19 System.out.println("Ret Val = " + obj); > 20 return true; > 21 } > 22 > 23 function boolean retB(Object obj1, Object obj2) { > 24 System.out.println("Ret Val 1 = " + obj1); > 25 System.out.println("Ret Val 2 = " + obj2); > 26 return true; > 27 } > > > > So what I am doing is very quick and very simple to reproduce. What is > happening is that when i run the program I am getting a class cast > exception > which is very very strange. > > > At first I thought it was tied only to the OR statement because if I > break > the rule into two rules (one for each of the or conditions) it works > fine. > > But after playing with it a little further I get a lot of other strange > class cast exceptions. > > For instance if I replace line 12 (eval(retB($classA, $classD))) with > eval(retA($classA)) it works fine, but if I replace it with > eval(retA($classD)) I get another class cast exception. Another > strainge > issue....if switch lines 4 and 5 and keep line 12 as eval(retA($classD)) > that previously failed, it now passes, but if I change line 12 back to > eval(retA($classA)) which previously passed it now fails..... > > There are a few other combinations that produce errors as well. Just > seems > to be a fundamental flaw in the logic and I'm curious if anyone else has > seen this? > > Thanks! > > Joshua > > P.S. > > Also I've noticed an issue with the manual example 6.36 > > This does not seem to work for me > pensioner : (or Person( sex == "f", age > 60 ) > Person( sex == "m", age > 65 ) ) > > > But this does > (or pensioner : Person( sex == "f", age > 60 ) pensioner : > Person( sex == "m", age > 65 ) ) > > > > > Although both formats are stated as working in the manual. > > > > > > >