Re: Is it possible to clone an object

From:

"Igor Tandetnik" <itandetnik@mvps.org>

Newsgroups:

microsoft.public.vc.atl

Date:

Fri, 15 Dec 2006 18:00:39 -0500

Message-ID:

<eTJdXzJIHHA.4992@TK2MSFTNGP04.phx.gbl>

John <John@discussions.microsoft.com> wrote:

Is it possible to clone (i.e. copy operator) an ATL object?
Say for instance I create the following object;

////////
// create an instance of some object and set some properties
///////
double d = 1.234;
float f = 5.678;
long l = 3;
CComPtr<ISomeObject> m_SomeObj1;
m_SomeObj1.CoCreateInstance(__uuidof(SomeObject));
m_SomeObj1->put_DoubleValue(d);
m_SomeObj1->put_FloatValue(f);
m_SomeObj1->put_LongValue(l);

//////
// Now I want to create a copy of this object with the current
// parameters into another object;
//////
CComPtr<ISomeObject> m_SomeObj2;
m_SomeObj2 = m_SomeObj1;

This would work, but it doesn't clone anything, it simply AddRef's the
old instance.

In general, you cannot clone an arbitrary COM object. An object may of
course provide a Clone() method or similar, returning a copy of itself.
Objects that support persistence can usually be cloned by serializing
them into a stream, then deserializing into a fresh instance.
--
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