On Thu, Oct 23, 2014 at 10:39:34AM +0530, Shriramana Sharma via
Digitalmars-d-learn wrote:
> IIUC the whole deal with not allowing ref parameters to point to
> rvalues is the fear that they may be returned outside the function,
> but it seems this is already possible:
>
> module reftest ;
> import std.stdio ;
> struct Pair {
> int x, y ;
> this (int x_, int y_) { x = x_ ; y = y_ ; writeln("Pair constructed") ;
> }
> auto handle() { return this ; }
> }
> void main() {
> auto P = Pair(1, 2).handle ;
> writeln(typeof(P).stringof) ;
> P.x = 3 ;
> writeln(P.x, ' ', P.y) ;
> }
>
> Running this makes it clear that only the one Pair object is ever
> constructed. But I don't understand how it is that the type of P is
> Pair and not ref(Pair).
[...]
ref is a storage class, not a type constructor. There is actually no
such type as ref(Pair). The 'ref' applies only to the function
parameter (or return value), NOT to whatever it gets assigned to.
T
--
Microsoft is to operating systems & security ... what McDonalds is to gourmet
cooking.
