Re: Accessing ClassA's properties from within ClassB

From:
"Igor Tandetnik" <itandetnik@mvps.org>
Newsgroups:
microsoft.public.vc.atl
Date:
Sat, 26 Jul 2008 16:27:55 -0400
Message-ID:
<eottZ417IHA.1196@TK2MSFTNGP05.phx.gbl>
"Phil Goddard" <PhilGoddard@discussions.microsoft.com> wrote in message
news:FBECDFDE-96C3-429C-8583-EF831C6BFE00@microsoft.com

The design I have in mind is for the ATL class methods to accept
other ATL class objects as their input, I then extract the pointer to
the C++ object in the input class and use it's (C++) methods to do
what I need to do.


If you insist, you can do the following. Define a new IID in your code
(say, IID_ClassA), don't publish it anywhere. In ClassA's interface map,
add

COM_INTERFACE_ENTRY_IID(IID_ClassA, ClassA);

Now your classes can query IClassA interface pointer for IID_ClassA, and
get back raw ClassA pointer (assuming IClassA is indeed implemented by
ClassA - otherwise QI will fail). Rememeber that, even though QI for
IID_ClassA returns raw class rather than an interface pointer, it still
AddRef's internally, and you need to Release to balance out the
reference count.
--
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

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