Cache Persistent 클래스는 다음과 같은 메소드를 overriding할 수 있도록 되어 있습니다. 오브젝트로 %Save()호출시에 이 메소드가 먼저 호출됩니다.

예제 소스를 보시고 참고하시기 바랍니다.

Class A Extends (%Persistent) {

Property LastModifiedAs%Date;
Property RegDateAs%Date;

///
/// This callback method is invoked by the <METHOD>%Save</METHOD> method to
/// provide notification that the object is being saved. It is called before
/// any data is written to disk.
///
/// <P><VAR>insert</VAR> will be set to 1 if this object is being saved for the first time.
///
/// <P>If this method returns an error then the call to <METHOD>%Save</METHOD> will fail.
Method %OnBeforeSave(insert As %Boolean) As %Status [ Private ]
{
ifinsert s ..RegDate=$h
s ..LastModified= $h
quit$$$OK
}

...

}