Using Caché Objects - InterSystems Documentation

Types of Classes
Embeddable Objects
Note:
Caché does not support polymorphic serial objects in persistent containers.
3.2.3.1 Embedded Objects in Memory and on Disk
When a new instance of an object containing an embedded object is created, the %New
method (or the analogous New command in Caché Basic) automatically creates an in-memory
instance of the object.
For example, consider an Address class:
Class MyApp.Address Extends %SerialObject [ClassType = serial]
{
Property Street As %String(MAXLEN=80);
Property City As %String(MINLEN=3);
Property State As %String(MINLEN=2);
}
Once defined, the Address class can be used as an embedded object attribute for a persistent
object class such as Patient:
Class MyApp.Patient Extends %Persistent [ClassType=persistent]
{
Property Name As %String;
Property Home As Address;
}
In memory, this Home property can be used as any other object-valued property:
// Open a persistent patient object
Set patient = ##class(MyApp.Patient).%OpenId(22)
// Get the patient's city and state from its Home address
Set city = patient.Home.City
Set state = patient.Home.State
Using Caché Objects 19