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Q201050: PRB: Custom AppWizard Based On COM Project Uses Same GUIDs

Article: Q201050
Product(s): Microsoft C Compiler
Version(s): 5.0,6.0
Operating System(s): 
Keyword(s): kbwizard kbVC kbVC500bug kbVC600bug kbAppWizard kbCustomWizard kbDSupport kbBug kbGrpDS
Last Modified: 12-JUN-2002

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The information in this article applies to:

- Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

A custom AppWizard based on an existing Component Object Model (COM) or
automation project does not create new GUIDs for components of new projects.
Therefore, projects based on this custom AppWizard generate objects with the
same CLSID (class ID) and IID. Type libraries for these objects will have the
same CLSID.

Once the new object is registered, programs expecting to load the original object
will load the new one instead.

CAUSE
=====

The new custom AppWizard templates contain the GUIDs copied from the base
project. The custom AppWizard generates new projects with a copy of those
original GUIDs, unlike the standard AppWizards which substitute macros in the
templates with new GUIDs.

RESOLUTION
==========

Modify the custom AppWizard project to automatically create new GUIDs using the
following steps:

1. Edit the template files, replacing GUIDs with appropriate macro names.

2. Set the macros to new GUIDs in the InitCustomAppWiz() function.

See the MORE INFORMATION section for specific instructions on implementing these
steps.

STATUS
======

Microsoft is researching this problem and will post new information in the
Microsoft Knowledge Base as it becomes available.

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

A custom AppWizard based on an existing project creates template files - such as
Rott.cpp, Root.h, Root.odl and Root.reg - which replace the base class names
with macros. The new templates preserve existing class definitions and
implementation codes, including the GUIDs of COM objects.

A custom AppWizard based on standard steps uses macros to generate new GUIDs and
then formats the GUIDs when it creates a new project. The standard AppWizard
dialog pages add the macro values to the macro dictionary. However, these macro
values are not available for use in custom AppWizards which do not use the
standard steps. An "unknown macro" error results when the custom AppWizard
generates new project files.

The following shows how to work around this problem. After applying the
instructions, your custom AppWizard project should generate new projects with
unique GUIDs.

Edit the template files
-----------------------

In the template files, replace GUID occurrences with macros. Each unique GUID
needs a macro, and each unique representation of that GUID needs a macro, too.
For consistency with the standard macros, use the following macro names:

+-----------------------------------------------------------------+
| $$APP_CLSID_REG$$     | A 1st GUID in normal format             | 
+-----------------------------------------------------------------+
| $$APP_CLSID$$         | The 1st GUID formatted as a C structure | 
+-----------------------------------------------------------------+
| $$DISPIID_CLSID_ODL$$ | A 2nd GUID in normal format             | 
+-----------------------------------------------------------------+
| $$DISPIID_CLSID$$     | The 2nd GUID formatted as a C structure | 
+-----------------------------------------------------------------+
| $$LIB_CLSID_ODL$$     | A 3rd GUID in normal format             | 
+-----------------------------------------------------------------+

In the Template Files folder of the custom AppWizard, make the following changes
to the files:

- Root.cpp: Use $$APP_CLSID$$ for the static const CLSID variable and
  $$APP_CLSID_REG$$ in comments.

- Root.odl: Use $$LIB_CLSID_ODL$$ for the uuid() attribute on the library. Use
  $$DISPIID_CLSID_ODL$$ for the uuid() attribute on the dispinterface. Finally,
  use $$APP_CLSID_REG$$ for the uuid() attribute on the coclass.

- Root.reg: Use $$APP_CLSID_REG$$ for all of the CLSID keys.

- DOC.H: Use $$DISPIID_CLSID$$ for the static const IID variable and
  $$DISPIID_CLSID_ODL$$ in comments.

NOTE: You will have to use new macro names if you are implementing multiple COM
interfaces, classes, etc.. For example, you will need to create macros for any
new coclasses your project defines in Root.odl.

TIP
---

Several standard header files contain a defined name including a GUID. This GUID
is not related to any automation capability, but it provides a unique name
designed to prevent recursive header file inclusions. The name begins with AFX_
and ends with __INCLUDED_. The template files Root.h, Doc.h, View.h, and perhaps
others, contain this construct. It appears at the beginning and end of generated
header files in code similar to the following:

     #if !defined(AFX_ME_H__DCE12ACA_4F12_11D2_AC7F_0060081982D5__INCLUDED_)
     #define AFX_ME_H__DCE12ACA_4F12_11D2_AC7F_0060081982D5__INCLUDED_
     ...
     #endif // AFX_ME_H__DCE12ACA_4F12_11D2_AC7F_0060081982D5__INCLUDED_

Replace the name in the three places it occurs in each header file with:

     $$FILE_NAME_SYMBOL$$_INCLUDED_

The AppWizard framework will replace $$FILE_NAME_SYMBOL$$ with a new unique name
when the custom AppWizard generates files.

Add new macros to the dictionary
--------------------------------

This section illustrates one way to create new GUIDs in the correct format. It
uses the RPC functions UuidCreate() and UuidToString(). These functions require
the library Rpcrt4.lib. You will need to use the following steps to add
Rpcrt4.lib to the custom AppWizard project:

1. From the Project menu, click Settings.

2. From the list Settings for, select "All Configurations".

3. Click the Link tab. From the Category list, select "General".

4. In the Object/library modules box, type "rpcrt4.lib" (without the quotation
  marks). Click OK.

Now, copy and paste the following code into the custom AppWizard just before the
first function in the <ProjectName>Aw.cpp file:

     #include <rpcdce.h>;
     static GUID        Guid;

     static const char *NewGuid()
     {
        static char szGuid[38];
        unsigned char *pszGuid;
        UuidCreate( &Guid );
        if (RPC_S_OK != UuidToString( &Guid, &pszGuid ))
               return NULL;
        lstrcpyn(szGuid, (char *)pszGuid, sizeof(szGuid) );
        RpcStringFree( &pszGuid );
        return szGuid;
     }
     static const char *GuidCStruct()
     {
        static char szStruct[ 83 ];
        static const char *pszFmtStruct = "{ 0x%x, 0x%x, 0x%x, { 0x%x, 0x%x,"
                                 " 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x } }";

        sprintf( szStruct, pszFmtStruct, Guid.Data1, Guid.Data2,
         Guid.Data3, Guid.Data4[0], Guid.Data4[1], Guid.Data4[2],
         Guid.Data4[3], Guid.Data4[4], Guid.Data4[5], Guid.Data4[6],
         Guid.Data4[7] );
        return szStruct;
     }

At the end of the InitCustomAppWiz() function, add the following code:

     m_Dictionary["APP_CLSID_REG"] = NewGuid();
     m_Dictionary["APP_CLSID"] = GuidCStruct();
     m_Dictionary["DISPIID_CLSID_ODL"] = NewGuid();
     m_Dictionary["DISPIID_CLSID"] = GuidCStruct();
     m_Dictionary["LIB_CLSID_ODL"] = NewGuid();

Build the custom AppWizard project. New projects based on this custom AppWizard
contain unique GUIDs unique.

REFERENCES
==========

For more information on the InitCustomAppWiz function, see the following
documentation in the MSDN library:

Visual C++ Documentation, Using Visual C++, Visual C++ Programmer's Guide,
Beginning Your Program, Details, AppWizard Programming Reference, CCustomAppWiz,
CCustomAppWiz::InitCustomAppWiz

For more information on the RPC functions, see the following documentation in the
MSDN library:

Platform SDK, Networking and Distributed Services, Remote Procedure Call (RPC),
Reference, Function Reference; RPC Functions; UuidCreate() and UuidToString()

Additional query words:

======================================================================
Keywords          : kbwizard kbVC kbVC500bug kbVC600bug kbAppWizard kbCustomWizard kbDSupport kbBug kbGrpDSTools kbNoUpdate kbISS 
Technology        : kbVCsearch kbAudDeveloper kbVC500 kbVC600 kbVC32bitSearch kbVC500Search
Version           : :5.0,6.0
Issue type        : kbprb
Solution Type     : kbpending

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