[Moderator's note: also posted to comp.lang.c++.moderated, apparently.]

Snyder brian scott wrote:

> Hello.  I'm curious as I've been going through reading/learning about
> exception handling in C++, I've started using the auto_ptr template
> class, and
> it seems to me, that even if you don't need to use it for 'resource
> aquisation' type model, it is still very usefull to gaurantee no memory
> leaks,
> so is there ever a situation where you wouldn't want to use it, or
> should I
> say, is there ever a situation where you don't want to use it, over a
> regular
> pointer to an object?
>
> Thanx,
>   brian

I want to add more questions to brian's ones.
I was using the auto_ptr implementation from RogueWave
and what I found is strange. the ownership is set with the
pointer value.
When you pass ownership from one source auto_pr to a
target auto_ptr, the source auto_ptr is set to 0.

So it means that we can never have 2 auto_ptrs of the same pointer.

    ex :int* pi = new int(2)
          auto_ptr<int> owner1 = p;  <---- owner1 is owner and holds p
          auto_ptr<int> owner2 = owner1; <--- owner2 is owner, holds p
but
owner1
                                                    now is no more owner
and holds NULL.

I read the CD2 but I didn't find something explicit about this kind of
behaaviour.

auto_ptr is a single owner solution. but nothing say that it must be a
single holder
solution too.

Could you give informations about this.

~Xavier

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Xavier Huet <xavier.huet@sophia.siemens-scg.com> writes:

> I was using the auto_ptr implementation from RogueWave

> When you pass ownership from one source auto_pr to a
> target auto_ptr, the source auto_ptr is set to 0.

That's correct, it's required in the FDIS.  The auto_ptr specification
has been modified since the CD2.

--
Alexandre Oliva
mailto:oliva@dcc.unicamp.br mailto:aoliva@acm.org
http://www.dcc.unicamp.br/~oliva
Universidade Estadual de Campinas, SP, Brasil


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