Re: copy from IUnknown* to CComObjectRoot

From:

"Igor Tandetnik" <itandetnik@mvps.org>

Newsgroups:

microsoft.public.vc.atl

Date:

Thu, 26 Feb 2009 19:43:05 -0500

Message-ID:

<uNhDbRHmJHA.4180@TK2MSFTNGP04.phx.gbl>

PaulH <paul.heil@gmail.com> wrote:

I have an ATL COM object that implements an ATL collection of another
ATL COM object. What I would like to do is essentially what I have in
the code below, I'm just not sure how to implement it. As is, the code
compiles, but when I read the iterator back, the collection is full of
empty objects suggesting the copy isn't deep enough.

typedef std::vector< CComObjectEmbed< CMyObj > > ContainerType;

STDMETHODIMP CMyCollection::Add( IMyObj* pObj )
{
CComObjectEmbed< CMyObj > item;
item = pObj; // ???

This compiles because CComObjectEmbed has this constructor:

CComObjectEmbed(void* pv) {m_pOuterUnknown = (IUnknown*)pv;}

As you see, what it does is nowhere near what you seem to think it does.

I'm not sure what you are trying to achieve. Why not just have a
collection of IMyObj* pointers? Note that there's no guarantee that
there's an instance of CMyObj behing IMyObj*. Somebody could provide
their own implementation of IMyObj, and pass that to you.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925