HOWTO: Override IUnknown Methods in an ATL Server

• The Microsoft Active Template Library (ATL) 3.0, included with:
  • Microsoft Visual C++, 32-bit Editions, version 6.0

SUMMARY

This article shows how to override the IUnknown methods (AddRef, Release and QueryInterface) in an ATL server.

MORE INFORMATION

When the client calls AddRef, Release or QueryInterface, the following functions that can be overridden are called:

CComObjectRootEx<>::InternalAddRef()
CComObjectRootEx<>::InternalRelease()
CComObjectRootBase::InternalQueryInterface() 

ULONG InternalAddRef()
{
        // do something
        return CComObjectRootEx<_ThreadModel>::InternalAddRef();
}

ULONG InternalRelease()
{
	// do something
	return CComObjectRootEx<_ThreadModel>::InternalRelease();
}

HRESULT WINAPI InternalQueryInterface(void* pThis, const _ATL_INTMAP_ENTRY* pEntries, REFIID iid, void** ppvObject)
{
	// do something
	return CComObjectRootBase::InternalQueryInterface(pThis, pEntries, iid, ppvObject);
} 

Additional query words:

Keywords : kbCOMt kbVC600 kbATL300 kbGrpMFCATL kbArchitecture
Version : WINDOWS:3.0
Platform : WINDOWS
Issue type : kbhowto