Q131044: FIX: ClassWizard Incorrectly Reads LPDISPATCH Params from .TLB

Article: Q131044
Product(s): Microsoft C Compiler
Version(s): winnt:2.0,2.1,4.0,4.1,4.2
Operating System(s): 
Keyword(s): kbole kbwizard kbAutomation kbMFC kbVC150bug kbVC151bug kbVC152bug kbVC200 kbVC200bug k
Last Modified: 06-MAY-2001

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The information in this article applies to:

- The ClassWizard, used with:
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.5, 1.51, 1.52 
   - Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 4.0, 4.1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
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SYMPTOMS
========

ClassWizard generates improper COleDispatchDriver derived member functions for
methods that contain one or more LPDISPATCH* parameters. Specifically,
ClassWizard generates member functions using a LPDISPATCH parameter instead of
LPDISPATCH*. In other words, the asterisk (*) is missing.

RESOLUTION
==========

To correct this problem, you must edit the COleDispatchDriver derived member
directly.

For example, assume there is a type library (.TLB file) for an object that
supports a method that returns a void and accepts an LPDISPATCH* as its only
parameter. When ClassWizard reads the .TLB file, it generates a new class from
COleDispatchDriver. The method for the member function that returns a void and
accepts an LPDISPATCH* parameter ends up with this incorrect definition:

     void ITestObject::TestMethod(LPDISPATCH lpDispPtr)
     {
        static BYTE BASED_CODE parms[] =
           VTS_DISPATCH;
        InvokeHelper(0x1, DISPATCH_METHOD, VT_EMPTY, NULL, parms,
           lpDispPtr);
     }

To correct this problem, change the parameter type to LPDISPATCH*, and modify the
parms[] array so that it contains a corresponding VTS_PDISPATCH entry instead of
VTS_DISPATCH, as illustrated here:

     void ITestObject::TestMethod(LPDISPATCH* lpDispPtr)
     {
        static BYTE BASED_CODE parms[] =
           VTS_PDISPATCH;
        InvokeHelper(0x1, DISPATCH_METHOD, VT_EMPTY, NULL, parms,
           lpDispPtr);
     }

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This was fixed in Visual C++ version 5.0.

Additional query words:

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Keywords          : kbole kbwizard kbAutomation kbMFC kbVC150bug kbVC151bug kbVC152bug kbVC200 kbVC200bug kbVC210bug kbVC400bug kbVC410bug kbVC420 kbVC420bug kbVC500fix kbClassWizard kbGrpDSMFCATL kbGrpDSTools kbbuglist kbfixlist
Technology        : kbVCsearch kbAudDeveloper kbClassWizard
Version           : winnt:2.0,2.1,4.0,4.1,4.2
Issue type        : kbbug
Solution Type     : kbfix

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