INFO: Visual C++ 5.0 Readme, Wizard and User-Interface Issues

ID: Q165686

The information in this article applies to:

Microsoft Visual C++, 32-bit Editions, version 5.0

SUMMARY

Wizard and other User-Interface Issues

Use the ATL Object Wizard to Create ATL Objects ATL Proxy Generator May Not Properly Destroy VARIANTARGs Two New Template Variables Available to Custom AppWizards Problems with ClassWizard Generated Wrapper Classes for Visual Basic 5.0 ActiveX Servers Newly Added Classes May Not be Displayed in the ClassView ATL Controls in Visual Basic 5.0 Containers Development Environment is Unresponsive While Processing a VBScript Macro Add Microsoft Transaction Server Libraries to your Proxy/Stub Makefile ClassView's Add Method and Add Property Dialogs Sometimes Allow Illegal Return Types for Custom Interfaces

MORE INFORMATION

Use the ATL Object Wizard to Create ATL Objects

Last-minute testing revealed that the ATL ClassWizard can reset properties while editing interfaces and that the ATL ClassWizard allows users to create different interfaces with the same name. This is a known problem and Microsoft is working on it.

Workaround

Once you have used the ATL Com AppWizard, use the ATL Object Wizard to create new ATL objects.

To Access the ATL Object Wizard:

Right-click your project's classes in ClassView to display the shortcut menu.

Click the New ATL Object command.

In the left pane of the ATL Object Wizard dialog box, click Objects.

Click the Simple Object icon.

Click Next.

Use the resulting ATL Object Wizard Properties dialog box to define your ATL object.

ATL Proxy Generator May Not Properly Destroy VARIANTARGs

If you have used the multicast component of the ATL Proxy Generator to generate ConnectionPoint broadcast code, (code that calls all active connections on a connection point), then one or more of the generated functions employs zero or more VARIANTARGs that are local to each function. (VARIANTARG is typed as VARIANT using typedef in oaidl.h.) Correct use of VARIANT includes a VariantInit call on the VARIANT before its use and VariantClear afterward. (VariantInit sets a VARIANTARG to a known empty state, VariantClear sets it back to a known state and frees all memory used by the VARIANTARG.) The multicast component calls VariantInit for each VARIANTARG but does not call VariantClear. In some cases, this may result in memory leaks.

Workaround

Manually add call(s) to VariantClear to the code that is generated by the multicast component. An alternative is to change all uses of VARIANTARG to CComVariant and remove the calls to VariantInit because CComVariant calls VariantInit in the constructor and VariantClear in the destructor.

Two New Template Variables Available to Custom AppWizards

root_oem Same as 'root' except translated to the OEM character set. Affects only upper ASCII characters in the project name (such as an umlauted character).

HM_FILE_OEM Same as 'HM_FILE' except translated to the OEM character set. Affects only upper ASCII characters in the project name (such as an umlauted character).

The Visual C++ tools work with the ANSI character set. Batch files, such as makehelp.bat, work with the OEM character set--a legacy from the days of DOS 1.0 that still exists. Most printable characters in these two sets are the same. However, there are some differences in some of the upper ASCII values used for European characters such as those that use an umlaut.

Problems with ClassWizard-Generated Wrapper Classes for Visual Basic 5

ActiveX Servers

With Visual Basic 5.0 you can create ActiveX Automation servers with methods that can take Optional and Default parameters of any Visual Basic intrinsic type. If you use MFC and want to access an object of a Visual Basic ActiveX Automation server, you would, typically, use ClassWizard to read the type information of the Visual Basic object and generate a class that wraps the functionality of the Visual Basic Automation object. C++ does not have optional or default parameters and so the wrapper class that ClassWizard generates will not mark parameters as Optional or Default.

For example, if you have a Visual Basic Server with the following function:


   Function function2(Optional parm1 As Integer = 5)

   MsgBox parm1

   End Function

ClassWizard will generate the following C++ wrapper function:


   VARIANT _MyVBObj::function2(short* parm1)

   {
    VARIANT result;
    static BYTE parms[] = VTS_PI2;

    InvokeHelper(0x60030001, DISPATCH_METHOD, VT_VARIANT,

     (void*)&result, parms, parm1);

    return result;
   }

If you call the ClassWizard generated function from your MFC program, you will have to pass the argument even though Visual Basic marked it as Optional.

Workaround

Override the function that ClassWizard generates with versions of the function that take only the parameters you wish to pass. For example, in the preceding case, if you didn't want to pass the optional parameter, override the ClassWizard generated function as follows:


   VARIANT _MyVBObj::function2()

   {
    VARIANT result;

    InvokeHelper(0x60030001, DISPATCH_METHOD, VT_VARIANT,

     (void*)&result, NULL);

    return result;
   }

In the preceding case, the default parameter for the Visual Basic server's function2 would be used.

Newly Added Classes May Not be Displayed in the ClassView

Dependency scanning in Visual C++ 5.0 has changed from earlier versions of Visual C++. Only files that are in the project will be scanned by ClassView. The External Dependency folder is automatically populated by the IDE and is not considered part of your project. If you want to see classes from header files that are in the External Dependencies folder, insert that file into your project. One easy way to insert a file from the External Dependencies folder is by dragging and dropping it into the project.

ATL Controls in Visual Basic 5.0 Containers

If you're using the IQuickActivate interface in Visual Basic 5.0, you must also support IPropertyNotifySink.

To use a control generated by the ATL Object Wizard in a Visual Basic 5.0 container, you must either add support for IPropertyNotifySink or remove dependence on the IQuickActivate interface. To remove IQuickActivate support, comment out the lines containing IQuickActivateImpl in the control's class inheritance list and in the COM interface map.

For example, if you generate a Full Control called MyCtl with the ATL Object Wizard, then go to MyCtl.h and comment out the line containing IQuickActivateImpl in the CMyCtl class inheritance list:


   class ATL_NO_VTABLE CMyCtl :
   ...
   // public IQuickActivateImpl<CMyCtl>

Also, comment out the line containing IQuickActivateImpl in the COM interface map in MyCtl.h:


<FIXEDTEXT><![CDATA[
   BEGIN_COM_MAP(CMyCtl)
   ...
   // COM_INTERFACE_ENTRY_IMPL(IQuickActivate)

Development Environment is Unresponsive While Processing a VBScript Macro

The Visual C++ user interface does not respond to mouse clicks or keystrokes until a macro finishes. Processing a lengthy macro gives the appearance that the user interface has hung. This design prevents indiscriminate interference between macros.

Add Microsoft Transaction Server Libraries to Your Proxy/Stub Makefile

If you are using a separate Proxy/Stub DLL created with the ATL COM Wizard, add the library mtxih.lib as the first library on the link line.

ClassView's Add Method and Add Property Dialogs Sometimes Allow Illegal Return Types for Custom Interfaces

The return type dropdown for Add Method and Add Property should be active only for dispinterfaces and for custom interfaces with the attribute 'local'. The return type is fixed at HRESULT for all other interface definitions--such as dual. Unfortunately, it is active for all non-dual interfaces. The midl compiler will fail with error 2269 when you build your project if you change the return type to something other than HRESULT or SCODE for a property or method in a custom interface that doesn't have the 'local' attribute.

Keywords :
Version : 5.0
Platform : NT WINDOWS
Issue type :