A version of IUnknownrenamed to enable a class to support both nondelegating and delegating IUnknowninterfaces in the same COM object. The interface supports the following three methods, in vtable order.

HRESULT NonDelegatingQueryInterface(
REFIID
iid
,
void**
ppvObject
);
ULONG
NonDelegatingAddRef(void);
ULONG NonDelegatingRelease(void);

Remarks

To use INonDelegatingUnknownfor multiple inheritance, perform the following steps:

Derive your class from an interface, for example, IMyInterface.

Include DECLARE_IUNKNOWNin your class definition to declare implementations of QueryInterface, AddRef, and Releasethat call the outer unknown.

Override NonDelegatingQueryInterfaceto expose IMyInterface with code such as the following:

if (riid == IID_IMyInterface) { return
GetInterface((IMyInterface *) this, ppv); } else { return
CUnknown::NonDelegatingQueryInterface(riid, ppv); }

Declare and implement the member functions of IMyInterface.

To use INonDelegatingUnknownfor nested interfaces, perform the following steps:

Declare a class derived from CUnknown.

Include DECLARE_IUNKNOWNin your class definition.

Override NonDelegatingQueryInterfaceto expose IMyInterface with the code such as the following:

if (riid == IID_IMyInterface) { return
GetInterface((IMyInterface *) this, ppv); } else { return
CUnknown::NonDelegatingQueryInterface(riid, ppv); }

Implement the member functions of IMyInterface. Use CUnknown::GetOwnerto access the COM object class.

In your COM object class, make the nested class a friend of the COM object class, and declare an instance of the nested class as a member of the COM object class.

Because you must always pass the outer unknown and an HRESULTto the CUnknownconstructor, you can't use a default constructor. You have to make the member variable a pointer to the class and make a new call in your constructor to actually create it.

Override the NonDelegatingQueryInterfacewith code such as the following:

if (riid == IID_IMyInterface) { return
m_pImplFilter-> NonDelegatingQueryInterface(IID_IMyInterface,
ppv); } else { return CUnknown::NonDelegatingQueryInterface(riid,
ppv); }

You can have mixed classes that support some interfaces through multiple inheritance and some interfaces through nested classes.