Re: Any chance of memory leak using smart pointers??

From:

"Igor Tandetnik" <itandetnik@mvps.org>

Newsgroups:

microsoft.public.vc.atl

Date:

Tue, 31 Oct 2006 14:00:49 -0500

Message-ID:

<#fVQi7R$GHA.3528@TK2MSFTNGP05.phx.gbl>

Usman Jamil <usman@advcomm.net> wrote:

I'm using smart pointers to call methods of a Com interface. Here is
example of how I use it in C++

IXyzPtr myObject("Abc.Xyz");

myObject->MyMethod();

myObject->Release();

Never call p->Release on a smart pointer. Always call p.Release().

Considering that there's no memory leak in MyMethod(). Is there any
chance that this code is leaking any memory. Also what is the
difference between
myObject->Release()

and

myObject.Release();

The former calls Release() on the underlying dumb pointer, but the smart
pointer still holds the dumb pointer. When smart pointer goes out of
scope, it will call Release() again in its destructor, and you will end
up with a too-low reference count. The COM object will likely be
destroyed prematurely.

The latter calls Release on the underlying dumb pointer, and also sets
the smart pointer to NULL. This is the right way to clean up the smart
pointer, if for some reason you don't want to wait for it to go out of
scope and perform cleanup in destructor.
--
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