Jochen Kalmbach's WebLog

Late-Binding in C++...

Maybe someone had already the opportunity to implement late binding of an COM-object in VC++... you also found out that this is very complicated…

In VB(6/A) or VB-Script it looks pretty simple:

  Dim wb As Object 

  Set wb = CreateObject("Word.Basic")
  wb.AppShow
  wb.FileNewDefault
  wb.Insert "This is a test"
  wb.FileSaveAs "c:sample.doc" 

But in C++ this will bring you to several 100 lines of code ;-(

MS provided some helper functions to make the life easier. This was great, but the code had some bugs… after using it in several projects I now found some bugs and have a “corrected” version of this helper-functions available:
http://blog.kalmbachnet.de/files/InvHelp.zip

With this helper-functions you can make the same code in C++ only with a little bit more lines of code:

  LPDISPATCH pdispWord; 

  CreateObject(OLESTR("Word.Basic"), &pdispWord);
  Invoke(pdispWord, DISPATCH_METHOD, NULL, NULL, NULL,
             OLESTR("AppShow"), NULL);
  Invoke(pdispWord, DISPATCH_METHOD, NULL, NULL, NULL,
             OLESTR("FileNewDefault"), NULL);
  Invoke(pdispWord, DISPATCH_METHOD, NULL, NULL, NULL,
             OLESTR("Insert"), TEXT("s"), (LPOLESTR)OLESTR("This is a test"));
  Invoke(pdispWord, DISPATCH_METHOD, NULL, NULL, NULL,
             OLESTR("FileSaveAs"), TEXT("s"), OLESTR("c:\sample.doc"));
  pdispWord->Release(); 

Late-Binding is also the recommended way to automate office application if you want to target more than one office version.