Q218982: HOWTO: Override IUnknown Methods in an ATL Server

Article: Q218982
Product(s): Microsoft C Compiler
Version(s): 3.0,6.0
Operating System(s): 
Keyword(s): kbCOMt kbVC600 kbATL300 kbGrpDSMFCATL kbArchitecture
Last Modified: 11-JUN-2002

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The information in this article applies to:

- The Microsoft Active Template Library (ATL) 3.0, included with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
   - Microsoft Visual C++.NET (2002) 
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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()

To override these functions, copy and paste the following functions in your ATL
class:

  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 kbGrpDSMFCATL kbArchitecture 
Technology        : kbVCsearch kbAudDeveloper kbATLsearch
Version           : :3.0,6.0
Issue type        : kbhowto

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