[phobos] is*Range + Qualified Types

[Steve Schveighoffer]

----- Original Message ----
> From: David Simcha <dsimcha at gmail.com>
> 
> On 9/17/2010 3:08 AM, Andrei Alexandrescu wrote:
> > 
> > I'm not sure how generalizable this is,  but it's a start. There is also the 
>remaining nagging issue of duplicating the  line
> > 
> >         return  typeof(return)(root);
> > 
> > which in other cases might expand to more  lines.
> 
> Shouldn't inout solve this once it's fully implemented?  Or  maybe template 
>this parameters + auto return types?

inout inside templates isn't really supported.  I'm not sure how it should 
work.  I know that inout is not supposed to be valid on a member variable 
because how does this work?

struct S
{
    inout int x; // what does this mean?
}

So how would this work?

struct S(T)
{
   T x;
}

S!(inout int) s;

The crux of this whole problem is that implicit conversions that make sense to a 
person are illegal to the compiler.  For example, it would make sense to a 
person that you could convert a Range!(N) into a Range!(const N), but the 
compiler sees them as distinct types.  I don't know the right answer of how to 
fix this except to revisit trying to define tail-const.

-Steve