Re: AddRef/Release side effects - is this ok?

From:
"Igor R." <igor.rubinov@gmail.com>
Newsgroups:
microsoft.public.vc.atl
Date:
Sun, 6 Sep 2009 06:54:33 -0700 (PDT)
Message-ID:
<d6923bff-f9ca-40d9-be7f-892465e6ad1f@h13g2000yqk.googlegroups.com>

The proxy never forwards these calls to the stub, except the very last
Release call when the proxy's own reference count reaches zero and it
destroys itself.


Too bad... So I can't hook the moment when the reference count drops
to 1 or any other number >0, right?

Why? What are you trying to achieve?


In my project I've got COM objects, whose sole purpose is to be
wrappers for the corresponding c++ objects: a) every COM wrapper
forwards calls to its implementation object; b) every COM wrapper
listens to some async. signals from the implementation object and
forwards them to COM client(s) through connection points.

The problem origins in (b): I have to ensure that COM wrapper outlives
any async. signal coming from the implementation. The best way to do
this is to bind the CComPtr to the slot functor:

wrapper::init()
{
  impl_->listenToSignals(bind(&wrapper::handler, CComPtr<wrapper>
(this)));
}

This implies that the COM-object cannot "die" until it's explicitly
disconnected from the signal, so when the user of my library wants to
get rid of such an object, he must call one more function (say, obj-

close()) before resetting his smart-ptr to the object -- which is not

just inconvenient, but also threatens the exception safety of user's
code.
I'd like to eliminate the need for this additional "finalization". The
only way I can see is to try and count those "internal" references,
and when the ref.count == internal_refcount, disconnect all the
signals.

Thanks!

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