Re: Trouble instantiatig callback object defined out-of-process

"Igor Tandetnik" <>
Sat, 9 Jun 2007 16:53:53 -0400
"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp> wrote in message

class CMySink :
    public CComObjectRootEx<CSingleThreadModel>,
    public ISink

CComObject<CMySink>* pObj = NULL;
HRESULT hr = CComObject<CMySink>::CreateInstance(&pObj);

This works when CMySink is defined locally (created with ATL Simple
Object wizard). But now I'm trying to define ISink in the server,
with #import of the server .tlb file. With that arrangement CMySink
compiles but the CreateInstance call will not compile:

1>c:\program files\microsoft visual studio
8\vc\atlmfc\include\atlcom.h(2612) : error C2259:
'ATL::CComObject<Base>' : cannot instantiate abstract class
1> with
1> [
1> Base=CMySink
1> ]
1> due to following members:
1> 'HRESULT IDispatch::GetTypeInfoCount(UINT *)' : is abstract
...and many more like this.

Don't derive ISink from IDispatch. Derive it from IUnknown, mark with
[oleautomation] attribute in IDL. Or else, make it a dispinterface and
use IDispEventImpl to implement it. It does not make sense to have a
dual interface for a callback.
With best wishes,
    Igor Tandetnik

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