Re: Implementation of shared_ptr

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 30 Jan 2009 15:37:10 -0800 (PST)
Message-ID:
<b587428d-784d-488d-92c7-bbea76dddf87@t26g2000prh.googlegroups.com>
On 30 jan, 17:08, Marcel M=FCller <news.5.ma...@spamgourmet.com> wrote:

James Kanze wrote:

On Jan 29, 9:41 pm, Marcel M=FCller <news.5.ma...@spamgourmet.com>
wrote:


    [...]

(The Boost documentation suggests making all of the
pointers to the object boost::shared_ptr. Which is fine, but
the compilers I use don't collaborate---this isn't a
boost::shared_ptr.)


What's wrong with your compiler?


It's conform with C++03, which says that this must have type T*
(and not type boost::shared_ptr<T>). Maybe this will change in
C++0x, but I don't think so (and I hope not).

On the other hand, I find that when an object is being
passed between threads, auto_ptr is more appropriate: once
the second thread has access, you don't want to allow access
from the first thread.


I would like to say that the most frequent use for reference
counts are thread-safe objects. Because as long as the object
is thread local or dedicated to exactly one thread at one
time, there is simply no need for reference counts.


It depends. But reference counted pointers have been oversold.

But if the object has (some) thread-safe methods, it makes
sense, that more than one thread holds an active reference to
the object.


Typically (and I know that there are exceptions), having
"thread-safe methodes" (whatever that actually medans) doesn't
buy you much. Thread safety is better handled at a higher
level.

--
me

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