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Q190148: BUG: ATL Object Wizard Doesn’t Add Entry to Connection Point Map

Article: Q190148
Product(s): Microsoft C Compiler
Version(s): 3.0,6.0
Operating System(s): 
Keyword(s): kberrmsg kbwizard kbActiveX kbCOMt kbConnPts kbVC600bug kbATL300bug kbGrpDSMFCATL kbNoU
Last Modified: 12-FEB-2002

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The information in this article applies to:

- The Microsoft Active Template Library (ATL) 3.0, used 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 
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SYMPTOMS
========

IConnectionPointContainer::FindConnectionPoint() might fail with the following
error:

  CONNECT_E_NOCONNECTION (0x80040200 - there is no connection for this
  connection id)

In ATL, AtlAdivse() wraps this call and returns the previous error code. In MFC,
AfxConnectionAdvise() wraps this call and returns FALSE on failure of this call.

CAUSE
=====

The ATL Object Wizard has an option to add connection point support to your COM
object. This enables connection points for your COM object by deriving your
object's class from IConnectionPointContainerImpl, adding a connection point map
(BEGIN_CONNECTION_POINT_MAP / END_CONNECTION_POINT_MAP), and adding an event
interface (dispinterface) definition to the .idl file and making it the default
source interface for the COM object. However, the wizard does not add the event
interface to the connection point map.

RESOLUTION
==========

Add the CONNECTION_POINT_ENTRY to the connection point map manually. Prefix
DIID_ to the event interface name to generate the IID for the entry. For
example:

     BEGIN_CONNECTION_POINT_MAP(CFoo)
        CONNECTION_POINT_ENTRY(DIID__DMyEvent)
     END_CONNECTION_POINT_MAP()

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this bug and will post new
information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a default ATL AppWizard EXE or DLL project.

2. Add an object using the ATL Object Wizard. (Choose New ATL Object from the
  Insert menu). Select any one of the different COM object types. On the
  Attributes tab of the ATL Object Wizard, select the Support Connection Points
  box.

3. In the <projectname>.idl file, you can see that in addition to the
  object's interface, there is an event interface which is the default source
  interface in the coclass of this object.

4. In the header file for the object class, you can see that the object class is
  derived from IConnectionPointContainerImpl, and there is a connection point
  map. Note that there is not a connection point entry for the event interface.

(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Jaganathan
Thangavelu, Microsoft Corporation.
(c) Microsoft Corporation 1998, All Rights Reserved.
Contributions by Jaganathan Thangavelu, Microsoft Corporation


Additional query words: IConnectionPointContainer IConnectionPoint

======================================================================
Keywords          : kberrmsg kbwizard kbActiveX kbCOMt kbConnPts kbVC600bug kbATL300bug kbGrpDSMFCATL kbNoUpdate 
Technology        : kbVCsearch kbAudDeveloper kbATLsearch
Version           : :3.0,6.0
Issue type        : kbbug
Solution Type     : kbnofix

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