For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.
CComObjectRootEx is essential; all ATL objects must have one instance of
CComObjectRootEx or CComObjectRoot in their inheritance.
CComObjectRootEx provides the default
QueryInterface mechanism based on COM map entries.
Through its COM map, an object's interfaces are exposed to a client when the client queries for an interface. The query is performed through
InternalQueryInterface only handles interfaces in the COM map table.
You can enter interfaces into the COM map table with the COM_INTERFACE_ENTRY macro or one of its variants. For example, the following code enters the interfaces
ISupportErrorInfo into the COM map table:
BEGIN_COM_MAP(CBeeper) COM_INTERFACE_ENTRY(IBeeper) COM_INTERFACE_ENTRY(IDispatch) COM_INTERFACE_ENTRY_TEAR_OFF(IID_ISupportErrorInfo, CBeeper2) END_COM_MAP()