Re: [boost] [optional] Thoughts on disallowing assignment for wrapped references.

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

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