Dependency of rule actions on rule variables

You define rule variables in the definitions part of a rule. If the variables of a rule cannot be instantiated by objects, the rule cannot execute and perform an action.

If a rule has variables and conditions, the rule can execute its else part only if the variables can be instantiated by objects and the conditions are not true.

The following rule always applies a discount because every customer receives a discount of at least 5 percent:

if 
	all of the following conditions are true:
		- the value of the shopping cart of customer is more than 100 
		- the category of customer is Gold 
then 
	set discount to 15 
else 
	set discount to 5 

However, you can change the rule by using the definitions part to give a discount to only customers in the Gold category:

definitions 
	set applicant to a customer in customers 
		where the category of this customer is Gold; 
if 
	the value of the shopping cart of applicant is more than 100 
then 
	set discount to 15 
else 
	set discount to 5