Microsoft KB Archive/201050

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

Article ID: 201050

Article Last Modified on 12/2/2003

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APPLIES TO


 * Microsoft Visual C++ 5.0 Enterprise Edition
 * Microsoft Visual C++ 6.0 Enterprise Edition
 * Microsoft Visual C++ 5.0 Professional Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Visual C++ 6.0 Standard Edition

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This article was previously published under Q201050



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:

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 . Click OK.

Now, copy and paste the following code into the custom AppWizard just before the first function in the Aw.cpp file: #include ; 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.

