Re: Promoting weak pointers

Tony Finch <dot@dotat.at>
19 Jun 2009 13:15:35 +0100 (BST)

          From comp.compilers
Related articles
[3 earlier articles]
Re: Promoting weak pointers m.helvensteijn@gmail.com (Michiel Helvensteijn) (2009-06-16)
Re: Promoting weak pointers m.helvensteijn@gmail.com (Michiel Helvensteijn) (2009-06-16)
Re: Promoting weak pointers m.helvensteijn@gmail.com (Michiel Helvensteijn) (2009-06-17)
Re: Promoting weak pointers bobduff@shell01.TheWorld.com (Robert A Duff) (2009-06-17)
Re: Promoting weak pointers andrew@tomazos.com (Andrew Tomazos) (2009-06-18)
Re: Promoting weak pointers armelasselin@hotmail.com (Armel) (2009-06-19)
Re: Promoting weak pointers dot@dotat.at (Tony Finch) (2009-06-19)
| List of all articles for this month |
From: Tony Finch <dot@dotat.at>
Newsgroups: comp.compilers
Date: 19 Jun 2009 13:15:35 +0100 (BST)
Organization: dotat labs
References: 09-06-047 09-06-055 09-06-057 09-06-060
Keywords: linker, parallel
Posted-Date: 21 Jun 2009 16:49:17 EDT

Robert A Duff <bobduff@shell01.TheWorld.com> wrote:
>Michiel Helvensteijn <m.helvensteijn@gmail.com> writes:
>
>> On Jun 16, 12:39 pm, Andrew Tomazos <and...@tomazos.com> wrote:
>>> if (my_weak_ptr != NULL)
>>> my_weak_ptr->do_something();
>
>> [Now I'm confused, too. This is an ordinary race condition of the kind
>> that every parallel program has to handle, and would present the same
>> issues no matter what kind of pointer it is. -John]
>
>It seems different, because in this case, the race condition is caused
>by the implementation (i.e. the garbage collector), not by the
>application.


I disagree. Weak pointers are inherently racy, so you have to write the
code to cope with that fact. For example,


ptr_copy = my_weak_ptr;
if (ptr_copy != NULL)
ptr_copy->do_something();


Tony.
--
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