Re: [boost] weak_ptr triple states

From: Pablo Aguilar (pablo.aguilar_at_[hidden])
Date: 2005-07-14 16:19:38

Just a thought...

Could replacing weak_ptr with optional<weak_ptr> do the job?

Pablo Aguilar

"Jaap Suter" <boost_at_[hidden]> wrote in message 
news:003101c588ad$ce174b40$4119059a_at_unknown...
> Are there compelling reasons not to add such a member function, i.e. a
> different shared_ptr implementation wouldn't be able to provide such a
> function?
>
> A friend of mine actually came up with a use case in his code, which is 
> what
> prompted this question. In pseudo-code, it looked like this:
>
> struct guarded_memory
> {
>    void*          memory;
>    weak_ptr    guard;
>
>    guarded_memory(void* m)
>        : guard(), memory(m) {}
>    guarded_memory(void* m, weak_ptr g)
>        : guard(g), memory(m) {}
>
>    void access()
>    {
>        if (guard.never_been_assigned_to_before())
>        {
>            // no guard means always accessible
>            do_something_with(memory);
>        }
>        else
>        {
>            if (shared_ptr p = guard.lock())
>            {
>                do_something_with(memory);
>            }
>        }
>    }
> };

[snip comments]

> Thanks,
>
> Jaap Suter