The IDLitData::AddDataObserver procedure method specifies an object (the Observer) that will be notified when the contents of the data object are changed.
The object specified as the Observer must implement three methods that form the data observer interface:
The OnDataChange method is called when the contents of a data object are changed, and the OnDataComplete method is called when the change messages are completed. This two-part notification process is used to allow observers of data to transact the change event and minimize the required system updates (such as graphic redrawing). The OnDataDelete method is called when the data item is deleted.
An object reference to an iTool component object that implements the data observer interface methods. When the contained data value changes, the Observer is notified of this change.