Boost logo

Boost :

Subject: Re: [boost] [optional] Thoughts on disallowing assignment for wrapped references.
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-09-06 10:31:23


Mostafa wrote:
> On Fri, 02 Sep 2011 11:10:01 -0700, Stewart, Robert
> <Robert.Stewart_at_[hidden]> wrote:
> > Mostafa wrote:
> >>
> >> Ahh, I disagree with that. IMO, if maybereff was not bound
> >> at construction time, then it should always remain
> >> "uninitialized".
> >
> > If the only way to make a non-empty optional<T&> is to
> > construct it from a reference, then it couldn't be used, for
> > example, as a function return type.
>
> A non-empty maybereff can be bound at construction time via
> construction from a T& or from construction from a non-empty
> optional<T&>.> The latter would allow it to be used as a
> function return type.

Right. When I wrote the above, however, I was thinking of the more generalized usage that is possible with optional, though I didn't say so:

optional<T>
f()
{
   optional<T> result;
   // do stuff
   return result;
}

Since copy assignment isn't permitted in your idea, that wouldn't work. That means even less generality, so a new type would definitely be in order if shown to be sufficiently useful.

_____
Rob Stewart robert.stewart_at_[hidden]
Software Engineer using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP http://www.sig.com

________________________________

IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.


Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk