Re: [boost] Futures Review - minor implementation details

20 Jan 2009


      ----- Original Message ----- 
From: "Anthony Williams" <anthony.ajw@gmail.com>
To: <boost@lists.boost.org>
Sent: Tuesday, January 20, 2009 12:40 PM
Subject: Re: [boost] Futures Review - minor implementation details
...
"vicente.botet" <vicente.botet@wanadoo.fr> writes:
...
Hi Anthony,
Some minor implementation details:
Why there is not other.future reset in
        shared_future(shared_future && other)
        {
            future.swap(other.future);
        }
        shared_future(unique_future<R> && other)
        {
            future.swap(other.future);
        }
How the move is made?
These are the constructors. The "future" member is initially NULL, so
the swap sets "other.future" to NULL whilst transferring the value
from "other.future" to "this->future"
OK, I see.
...
...
Is 
            future.swap(other.future);
            other.future.reset();  (1)
more efficient than
            future.reset(other.future);
            other.future.reset();
? Otherwise you can change it in:
The former avoids incrementing any reference counts. The
latter has to increase the reference count on *other.future just to
decrease it again with the reset.
I see.

Thanks,
Vicente