COM with ATL Versioning

Question

My Visual Studio 2008 ATL project has a control that defines a version number in several places. The IDL file:

uuid(56CD4ADB-B72D-4BF8-B5AC-6CA320EAD27D),
version(1.0),
helpstring("MyProject 1.0 Type Library")

The control's header file:

    class ATL_NO_VTABLE CMyControl :
        public CComObjectRootEx<CComSingleThreadModel>,
        public IDispatchImpl<IMyControl, 
             &IID_IMyControl, &LIBID_MyProjectLib, 
             /*wMajor =*/ 1, /*wMinor =*/ 0>,
            ...

And an rgs file:

MyCompany.MyProject.MyControl.1 = s 'MyControl Class'

What's the relationship between these version numbers? When I want to release version 2, do I increment all 3? And why does the the version in the registry script only have a 1 and not a 1.0?

Answer 1

You should check out Larry Osterman's series on COM and the minimial registry. It should shed a bit of light on what these numbers actually do

• http://beta.blogs.msdn.com/larryosterman/archive/2006/01/11/511647.aspx
• http://beta.blogs.msdn.com/larryosterman/archive/2006/01/10/511279.aspx
• http://beta.blogs.msdn.com/larryosterman/archive/2006/01/05/509731.aspx