Q153677: PRB: Implementing Stock Error Event in Custom OLE Control

Article: Q153677
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0
Operating System(s): 
Keyword(s): kbCtrl kbVBp400 kbGrpDSVB kbDSupport
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SYMPTOMS
========

Visual Basic generates an error message if the MFC Class Wizard's stock Error
event is implemented in a custom OLE Control.

For example, if you go to the OLE Events tab in the MFC Class Wizard and add the
stock Error event, you will get the following definition in the control's ODL
file:

      dispinterface _DTestEvents
      {
       properties:
       //  Event interface has no properties

       methods:
        // NOTE - ClassWizard will maintain event information here.
        //    Use extreme caution when editing this section.
        //{{AFX_ODL_EVENT(CTestCtrl)

        [id(DISPID_ERROREVENT)] void Error(short Number, BSTR*
         Description, SCODE Scode, BSTR Source, BSTR HelpFile,
         long HelpContext, boolean* CancelDisplay);

         .
         .

        //}}AFX_ODL_EVENT
        };

This will generate the following event stub in Visual Basic:

     Private Sub Test1_Error(Number As Integer, Description As String, _
              Scode As Error, Source As String, HelpFile As String, _
              HelpContext As Long, CancelDisplay As Boolean)

     End Sub

RESOLUTION
==========

To avoid the error generated by Visual Basic, you need to change the event
definition of the stock error event in the ODL such that the third parameter is
of type long instead of SCODE:

[id(DISPID_ERROREVENT)] void Error(short Number, BSTR* Description, long Scode,
BSTR Source, BSTR HelpFile, long HelpContext,boolean*CancelDisplay);

This will change the third parameter in the Visual Basic event stub from "Scode
As Error" to "Scode As Long," and the error will no longer be generated.

STATUS
======

This behavior is by design.

Additional query words: 4.00 vb4win vb4all vbctrl

======================================================================
Keywords          : kbCtrl kbVBp400 kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : WINDOWS:4.0
Issue type        : kbprb

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