Q198017: BUG: Unexpected Error Using ATL Interface Wizard to Add Methods

Article: Q198017
Product(s): Microsoft C Compiler
Version(s): 3.0,6.0
Operating System(s): 
Keyword(s): kbwizard kbAutomation kbVC600bug kbATL300bug kbGrpDSMFCATL kbCollectionClass
Last Modified: 13-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 
   - Microsoft Visual C++.NET (2002) 
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SYMPTOMS
========

The ATL Interface Wizard with Visual C++ 6.0 displays the following error
message:

  "Unable to create the function because the header or the
  implementation file could not be found."

when adding a method that has either SAFEARRAY(oleautomationtype)" or
"SAFEARRAY(oleautomationtype)*" as the variable type. oleautomationtype is an
OLE automation-compatible data type.

CAUSE
=====

This is due to a bug in the ATL Interface Wizard.

RESOLUTION
==========

Add these methods by manually editing the .idl, .h, and .cpp files.

The following shows the changes when adding two methods (called Test and Test2
that have SAFEARRAY(BSTR)* and SAFEARRAY(BSTR), respectively) to an interface
called IATLObj. IATLObj is implemented by an ATL class called CATLObj.

1. Add this code for the new methods in the .IDL file:

        interface IATLObj : IDispatch
        {
           [id(1)] HRESULT Test([out] SAFEARRAY(BSTR) *ppArrayBstr);
           [id(2)] HRESULT Test2([in] SAFEARRAY(BSTR) pArrayBstr);
        };

2. Add this code to the .H file for the ATL COM object:

        STDMETHOD(Test)(SAFEARRAY **ppArrayBstr);
        STDMETHOD(Test2)(SAFEARRAY *pArrayBstr);

3. And add this code to the .CPP file for the ATL COM object:

        STDMETHODIMP CATLObj::Test(SAFEARRAY **ppArrayBstr)
        {
           return S_OK;
        }

        STDMETHODIMP CATLObj::Test2(SAFEARRAY *pArrayBstr)
        {
           return S_OK;
        }

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

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

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

1. Create a new ATL/COM Application Wizard Project.

2. Insert a new ATL COM Object with the default settings.

3. Add a new method with the ATL COM Object Wizard by right-clicking the
  interface to add the method and by selecting "Add Method."

4. Give the method a name.

5. Add one parameter with SAFEARRAY(BSTR)* as the type For example: [out]
  SAFEARRAY(BSTR) *pArrayBSTR. Note that when you click OK on the "Add Method
  to Interface" dialog box, a message box appears with the error mentioned
  above.

REFERENCES
==========

For additional information, please see the following article in the Microsoft
Knowledge Base:

  Q196837 Compile Errors Result for Certain ATL Method Parameters

Additional query words:

======================================================================
Keywords          : kbwizard kbAutomation kbVC600bug kbATL300bug kbGrpDSMFCATL kbCollectionClass 
Technology        : kbVCsearch kbAudDeveloper kbATLsearch
Version           : :3.0,6.0
Issue type        : kbbug
Solution Type     : kbpending

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