DOCUMENT:Q218982  11-JUN-2002  [visualc]
TITLE   :HOWTO: Override IUnknown Methods in an ATL Server
PRODUCT :Microsoft C Compiler
PROD/VER::3.0,6.0
OPER/SYS:
KEYWORDS:kbCOMt kbVC600 kbATL300 kbGrpDSMFCATL kbArchitecture

======================================================================
-------------------------------------------------------------------------------
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) 
-------------------------------------------------------------------------------

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

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2002.