ATL对IDispatch的封装

		//CLSID_PolyCtl
		CComPtr<IUnknown> spUnk;
		spUnk.CoCreateInstance(__uuidof(Beeper));

		CComDispatchDriver spDisp = spUnk;

		CComVariant vResult;	
		HRESULT hr = spDisp.Invoke0(	
			L"Beep",				
			&vResult);		
		ATLASSERT( SUCCEEDED( hr ) );