Re: RValue Arrays

On Jul 21, 12:24 pm, David Abrahams <d...@[EMAIL PROTECTED]
> wrote:
> on Sun Jul 20 2008, rkldabs-AT-gmail.com wrote:
>
> > I was not sure about what is an rvalue array and hence a little
> > googling threw up the following site
"http://209.85.175.104/search?q=cache:r1-djlzAyBUJ:www.open-std.org/jt..."
>
> > I would like to know a little more about RValue Arrays. The standard
> > as far as I have understood does not clearly explain RValue arrays.
>
> I think the only thing that makes array rvalues different from other
> rvalues is that they never exist except as a subobject of some other
> rvalue.  For example:
>
>           struct X
>           {
>               int a[20];
>           };
>
> Now
>          X()
>
> is an rvalue of type X and
>
>          X().a
>
> would be an rvalue array... if I'm not mistaken, that is ;-)

This is quite interesting. Normally:

    X makeX();
    X& x = makeX();

Generates an error because a reference to non-const can not be bound
to r-value. On the other hand:

    int(&ra)[20] = makeX().a;

Does not generate an error. In other words, the compiler does not
treat a member of an r-value as an r-value.

I wonder if r-value arrays exist.

Max


-- 
      [ See http://www.gotw.ca/resources/clcm.htm
for info about ]
      [ comp.lang.c++.moderated.    First time posters: Do this! ]