Chapter 10 Expansion
Extension is a logical view of all persistent instances for a given sustainable class. Extensions can be obtained from the PersistenceManager, usually to specify the candidate object of the query.
GetCandIdateClass method returns a long-term capable class of the extended instance. HassUBClasses indicates whether the sub-class instance is included.
You can use the Iterator method to get an extension of an enumerator with all objects. Use it usually consume database resources, so when you are used, you should turn off the enumerator. You can use the enumerator as a parameter of the Close method , Close this enumerator. You can also call the Closeall method, turn off all open enumeors.
