【Fundamentals of ATL COM Objects】
The following illustration depicts the relationship among the various classes and interfaces used in defining an ATL COM object.
ATL implements IUnknown in two phases:
- CComObject, CComAggObject, or CComPolyObject implements the IUnknown methods.
- CComObjectRoot or CComObjectRootEx manages the reference count and outer pointers of IUnknown.
Other aspects of your ATL COM object are handled by other classes:
- CComCoClass defines the object's default class factory and aggregation model.
- IDispatchImpl provides a default implementation of the IDispatch portion of any dual interfaces on the object.
- ISupportErrorInfoImpl implements the ISupportErrorInfo interface that ensures error information can be propagated up the call chain correctly.
