AcRxObject AcDbObjectReactor AcDbEntityReactor
class AcDbEntityReactor : public AcDbObjectReactor;
dbmain.h
The AcDbEntityReactor class is designed to be used as a base class for custom reactor classes that want to receive notification when an entity object has had one of its modification methods called and has then been closed in order to commit any changes made. This reactor type can be attached only to entities, so it provides a way to distinguish changes made to entities versus changes made to any object.
Use this class by defining a class that inherits from AcDbEntityReactor. Instantiate an object of the class derived from AcDbEntityReactor, and add the newly created reactor object to the reactor chain by calling the addReactor method of the object you want notification on.
To prevent an infinite recursive loop, do not call AcRxObject::clone() within the openedForModify() entity transient reactor callback for an entity.
AcDbEntity, AcDbObject, AcDbDatabase