Re: Default Implementation for IUnknown

From:

Stefan Weber <stefan.weber@gmail.com>

Newsgroups:

microsoft.public.vc.atl

Date:

8 May 2007 01:44:28 -0700

Message-ID:

<1178613868.537369.319950@e51g2000hsg.googlegroups.com>

Yes you can. Something like this:

class MySink : public IDispEventSimpleImpl<0, MySink, &IID_IDispatch> {
    typedef IDispEventSimpleImpl<0, MySink, &IID_IDispatch> BaseClass;
public:
    BEGIN_SINK_MAP(MySink)
        SINK_ENTRY_INFO(0, IID_IDispatch, DISPID_VALUE, OnEvent,
&EventInfo)
    END_SINK_MAP()

    // |event| implements IHTMLEventObj[2|3|4]
    // return VARIANT_FALSE to cancel defaul action, VARIANT_TRUE to
allow
    VARIANT_BOOL STDMETHODCALLTYPE OnEvent(IDispatch* event);

    // Suitable for passing to attachEvent
    IDispatch* GetIDispatch() {
        return
reinterpret_cast<IDispatch*>(static_cast<BaseClass*>(this));
    }

private:
    static _ATL_FUNC_INFO EventInfo;

};

// In .cpp file
_ATL_FUNC_INFO MySink::EventInfo = {
    CC_STDCALL, VT_BOOL, 1, {VT_DISPATCH}

};

No I tried it using the input of Alexander and some other sources as
well. It looks like that:

class ATL_NO_VTABLE DOMEventHandler :
    public IDispEventImpl<1, DOMEventHandler, &DIID_HTMLElementEvents2,
&LIBID_MSHTML, 1, 1>
{
    typedef IDispEventImpl<1, DOMEventHandler, &DIID_HTMLElementEvents2,
&LIBID_MSHTML, 1, 1> BaseClass;

protected:
    long m_dwRef;

public:

    DOMEventHandler(void) {}
    virtual ~DOMEventHandler(void) {}

    void STDMETHODCALLTYPE OnClick(IHTMLEventObj *pEvtObj);

    BEGIN_COM_MAP(DOMEventHandler)
        COM_INTERFACE_ENTRY(IDispatch)
    END_COM_MAP()

    BEGIN_SINK_MAP(DOMEventHandler)
        SINK_ENTRY_EX(1, DIID_HTMLElementEvents2,
DISPID_HTMLELEMENTEVENTS2_ONCLICK, OnClick)
    END_SINK_MAP()

    ULONG InternalAddRef() { return AddRef(); }
    ULONG InternalRelease() { return Release(); }
    void FinalRelease() {}
};

Unfortunatly, this doesn't compile. I get the message that 'Lock',
'Unlock' and 'InternalQueryInterface' are not a member of
DOMEventHandler but I don't know what these methods are supposed to
do. Without the COM_MAP I also get error messages because the object
is used as follows:

    CComObject<DOMEventHandler>* pDEH;
    hr = CComObject<DOMEventHandler>::CreateInstance(&pDEH);
    CHECK_OK(hr);
    pDEH->AddRef();

    pDEH->DispEventAdvise(pDocument);
    VARIANT v;
    v.vt = VT_DISPATCH;
    v.pdispVal = (IDispatch*) pDEH;

Thus, I get the error that '_InternalQueryInterface' was not found
which is why I added the COM_MAP in the first place (but that in turn
lead to the problems mentioned above).

Any hints?

Thanks,

Stefan