Rule inheritance

One last important aspect of rule creation is the possibility of having a rule hierarchy. Just like classes, rules allow inheritance between them. If rule B inherits rule A, it will be the same as having all the conditions in rule A at the beginning of the conditions of rule B. The following table shows two rules using inheritance and their equivalent without it:

rule "A"
whens: String(this == "A")
thenSystem.out.println(s);
end

rule "B" extends "A"
when
  i: Integer(intValue > 2)
then  System.out.println(i);
end

 

rule "A"
whens: String(this == "A")
thenSystem.out.println(s);
end

rule "B"
whens: String(this == "A")i: Integer(intValue > 2)
thenSystem.out.println(i);
end

This can be a good strategy to manage rules that have repetitive ...

Get Mastering JBoss Drools 6 now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial