Re: error C2594: 'static_cast' and Multiple Inheritance

From:
"Igor Tandetnik" <itandetnik@mvps.org>
Newsgroups:
microsoft.public.vc.atl
Date:
Tue, 31 Oct 2006 07:57:58 -0500
Message-ID:
<#0chvwO$GHA.4320@TK2MSFTNGP02.phx.gbl>
"Barnab?" <eric.franc@gmail.com> wrote in message
news:1162281362.623827.74650@m73g2000cwd.googlegroups.com

class ATL_NO_VTABLE CTranslator :
public CComObjectRootEx<CComSingleThreadModel>,
.... };

The problem occures when I create a COM interface pointers.
CComPtr<CTranslator> moTranslations;


You are not supposed to do this. The template paramater of CComPtr is
supposed to be an interface pointer, not your implementation class. As
in CComPtr<ITranslator>.

error C2594: 'argument' : ambiguous conversions from 'CTranslator *'
to 'IUnknown *'


All classes implementing more than one interface would have this
problem, as they derive from IUnknown multiple times (once via each
implemented interface). This is normal. Using such a class as a paramter
to CComPtr is not.
--
With best wishes,
    Igor Tandetnik

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