BUG: Unexpected Error Using ATL Interface Wizard to Add Methods

• The Microsoft Active Template Library (ATL) 3.0, used with:
  • Microsoft Visual C++, 32-bit Editions, version 6.0

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."

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 kbGrpMFCATL kbCollectionClass
Version : WINDOWS:3.0
Platform : WINDOWS
Issue type : kbbug