How To Prevent Creation of Initial Macintosh Document

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In a Windows MFC application, a new document is initially created if the Command Line is empty. Since Macintosh applications do not have Command Lines, the open application Apple Event is sent to the application and is handled by _AfxOpenAppHandler(), which calls CreateInitialDocument() to open a new document:

  // From Visual C++ 4.0
   OSErr PASCAL _AfxOpenAppHandler(AppleEvent* pae,
                                   AppleEvent* paeReply,
                                   long lRefcon)
   {
     CWinApp* pApp;
     OSErr err = HandlerCommon(pae, lRefcon, pApp);
     if (err == noErr)
     {
       if (pApp->CreateInitialDocument())
         err = noErr;
       else
         err = errAEEventNotHandled;
     }
     AfxOleSetUserCtrl(TRUE);
     return err;
   }

   // From Visual C++ 4.0
   BOOL CWinApp::CreateInitialDocument()
   {
     if (m_pMainWnd != NULL)
       m_pMainWnd->SendMessage(WM_COMMAND, ID_FILE_NEW);
     else if (m_pDocManager != NULL)
     {
       POSITION pos = m_pDocManager->GetFirstDocTemplatePosition();
       if (pos != NULL)
       {
         CDocTemplate* pTemplate = m_pDocManager->GetNextDocTemplate(pos);

         // if MDI, or SDI but we haven't opened any documents yet,
         // open a new one
         if (pTemplate != NULL &&
           (pTemplate->IsKindOf(RUNTIME_CLASS(CMultiDocTemplate)) ||
           m_pDocManager->GetOpenDocumentCount() == 0))
         {
           OnFileNew();
         }
       }
     }
     return TRUE;
   }
				

When a new document is not needed, you can override CreateInitialDocument() and have it return TRUE. This is desirable to prevent the file type dialog from appearing in applications supporting multiple document types:

   BOOL CMyWinApp::CreateInitialDocument()
   {
     return TRUE;
   }