Multiple Inheritance by IDispatch

[ajitatif angajetor]

Hi everyone, I have a class that implements an interface that derives from IDispatch directly,and I want to add a new interface which also derives from IDispatch,and then derive my class from this interface too.Expectedly,my problem is ambiguouty (did I spell it correctly??).I use COM_INTERFACE_ENTRY2 macro,but i keep getting error "cannot instantiate abstract class" error in atlcom.h this is the IDL file:

library TheLibrary
{
	importlib("stdole2.tlb");
	[
		object,
		uuid(),
		dual,
		nonextensible,
		helpstring("Primary dispatch interface for the class."),
		pointer_default(unique)
	]
	interface ISomething : IDispatch
	{
	};

	[
		uuid(),
		helpstring("help string.")
	]
	coclass CSomething
	{
		[default] interface ISomething};

	[
		uuid(),
		nonextensible,
		helpstring("the new Interface"),
	]
	dispinterface INewInterface
	{
	properties:
	methods:
			[id(0), helpstring("method default"), local] HRESULT DefaultMethod(void);
        };

and this is the COM mapping

	BEGIN_COM_MAP(CSomething)
		COM_INTERFACE_ENTRY(ISomething)
		COM_INTERFACE_ENTRY2(IDispatch, ISomething)
		COM_INTERFACE_ENTRY(IObjectWithSite)
		COM_INTERFACE_ENTRY_IID(IID_IOleWindow, IDeskBand)
		COM_INTERFACE_ENTRY_IID(IID_IDockingWindow, IDeskBand)
		COM_INTERFACE_ENTRY(IDeskBand)
		COM_INTERFACE_ENTRY_IID(IID_IInputObject,IInputObject)
		COM_INTERFACE_ENTRY(IPropertyNotifySink)
		COM_INTERFACE_ENTRY(INewInterface)
	END_COM_MAP()

I tried using interface instead of dispinterface.Didn't help either.I know I'm missing something,but can't figure out what it is...

[Stuart Dootson]

ajitatif angajetor wrote:

ambiguouty (did I spell it correctly??)

No - ambiguity - close, though :-) Anyway - I've had a look through my code collection - I have a class that implements two IDispatch interfaces, in ATL 3.0 (it's an old VC6 project). Here's the relevant bit of the IDL:

[
    uuid(01b836c6-51c8-4476-bf15-ae91b0fe74f6),
    oleautomation,
    dual
]
interface ICommands : IDispatch
{
    [id(1), helpstring("method RereadEnvironment")] 
    HRESULT RereadEnvironment();
};

[ hidden, uuid(0309A24D-B3E7-4C6A-8ACD-B3F0F8FAA483) ]
coclass ApplicationEvents
{
    [default] dispinterface IDispApplicationEvents;
}

[
    uuid(6c5658bc-946b-4bc7-94bf-5530cad3d654)
]
coclass Commands
{
    [default] interface ICommands;
};

and code

class ATL_NO_VTABLE CCommands : 
    public CComObjectRootEx<CComSingleThreadModel>,
    public CComCoClass<CCommands, &CLSID_Commands>,
    public IDispatchImpl<ICommands, &IID_ICommands, &LIBID_DSWENVLib>,
    public IDispatchImpl<IApplicationEvents, &IID_IApplicationEvents, &LIBID_DSWENVLib>
{

BEGIN_COM_MAP(CCommands)
    COM_INTERFACE_ENTRY(ICommands)
    COM_INTERFACE_ENTRY2(IDispatch, ICommands)
    COM_INTERFACE_ENTRY(IApplicationEvents)
END_COM_MAP()
DECLARE_NOT_AGGREGATABLE(CCommands)

   <class continues>

Don't know if there's anything obvious there - the COM map looks very similar to yours - what about the inheritance? Do you have an IDispatchImpl inheritance for each IDispatch interface you want to implement?

[ajitatif angajetor]

:-D uuuuuuh,no. I added an IDispEventImpl to inheritance list and it worked.Great help,thanks:)

[Stuart Dootson]

Cool - glad I could help :-)