BAL VS IRL

Multiple Rule Variables – BAL vs IRL

          The way multiple rule variables are declared and instantiated in working memory varies between the BAL and IRL.

Business Action Language(BAL):

      Suppose if we assign ‘Customer’ class instance to a multiple variables using definitions of a rule they are treated as two different instances.

definitions

set ‘customer1’ to Customer;
set ‘customer2’ to Customer;

   Here customer1 and customer2 are treated as two different instances of class Customer and can be acted on independently.

 IRL:

If we consider the same example as above and define multiple variables in IRL as below:
when {
customer1: carrental.Customer();
customer2: carrental.Customer();
} then {
…
}

     Here the variables customer1 and customer2 will refer to the same Customer instance in working memory and may create conflicts.To ensure it refers to different instances we need to add a test as below:
when {
customer1: carrental.Customer();
customer2: carrental.Customer(?this != customer1);
} then {
…}