Rule variables

Making rules easier to understand

You might find parts of a rule difficult to understand. For example, the following rule uses the term of to chain together business terms:

if
	the value of the shopping cart of customer is less than 100 
then... 

You can shorten this chain of words by using a rule variable. For example, you can define a variable named cart to represent the business terms shopping cart and customer:

definitions
	set cart to the shopping cart of customer;
if
	the value of cart is less than 100 
then... 

One rule per rule variable

The scope of a variable is the rule that declares the variable. The name of the variable must be unique in the rule. After you define a variable, it can be used in any part of the rule.

In the following rule, the definitions part defines the variable Smith, which is then used in the if part of the rule.

definitions
	set Smith to a customer in customers; 
if
	the category of Smith is Gold 
then
	set discount to 10; 

When rule variables do not match data

A rule can define a rule variable that data cannot satisfy when an application calls the decision. For example, you might define a variable named 'low risk borrowers' for all the borrowers whose credit score is at least 200. However, when you run the rule against data from an application, the rule might not find any borrowers who match the rule variable. In this case, the rule variable behaves as a condition, and the rule cannot execute the actions in its then and else parts.

Restrictions on rule variable names

Do not use the following characters in the names of your variables:

Single quotation marks

If the name of a rule variable contains one or more spaces, you must enclose the name in single quotation marks when you define or use the variable. If a variable name contains only one word, quotation marks are optional.