PRB: Custom AppWizard Based On COM Project Uses Same GUIDs

ID: Q201050

The information in this article applies to:

Microsoft Visual C++, 32-bit Editions, versions 5.0, 6.0

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:

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

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:

From the Project menu, click Settings.

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

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

In the Object/library modules box, type rpcrt4.lib. 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
Version : winnt:5.0,6.0
Platform : winnt
Issue type : kbprb