Classification (IS/AS)

Classification operators create properties that determine whether an object belongs to the class specified. If the property argument does not belong to the class specified in the operator, the property returns NULL. Otherwise, the operator IS returns TRUE, and the operator AS returns the object passed as an argument.

Language

To implement classification operators, IS and AS operators are used.

Examples

asOrder(object) = object AS Order;

person = DATA Human (Order);
isMale (Order o) = person(o) IS Male;