Formatted read consumes input

[monarch_dodra]

On Friday, 7 September 2012 at 14:51:45 UTC, Steven Schveighoffer 
wrote:
> On Fri, 07 Sep 2012 10:35:37 -0400, monarch_dodra
>
> This looks ugly.  Returning a tuple and having to split the 
> result is horrible, I hated dealing with that in C++ (and I 
> even wrote stuff that returned pairs!)
>
> Not only that, but there are possible ranges which may not be 
> reassignable.
>
> I'd rather have a way to wrap a string into a ref-based input 
> range.
>
> We have three situations:
>
> 1. input range is a ref type already (i.e. a class or a pImpl 
> struct), no need to pass this by ref, just wastes cycles doing 
> double dereference.
> 2. input range is a value type, and you want to preserve the 
> original.
> 3. input range is a value type, and you want to update the 
> original.
>
> I'd like to see the library automatically make the right 
> decision for 1, and give you some mechanism to choose between 2 
> and 3.  To preserve existing code, 3 should be the default.
>
> -Steve

True...

Still, I find it horrible to have to create a named "dummy" 
variable just when I simply want to pass a copy of my range.

I think I found 2 other solutions:
1: auto ref.
2: Kind of like auto ref: Just provide a non-ref overload. This 
creates less executable bloat.

Like this:
--------
//Formatted read for R-Value input range.
uint formattedRead(R, Char, S...)(R r, const(Char)[] fmt, S args)
{
     return formattedRead(r, fmt, args);
}
//Standard formated read
uint formattedRead(R, Char, S...)(ref R r, const(Char)[] fmt, S 
args)
--------
This allows me to write, as I would expect:

--------
void main()
{
   string s = "x42xT";
   int v;
   formattedRead(s.save, "x%dx", &v); //Pyssing a copy
   writefln("[%s][%s]", v, s);
   formattedRead(s, "x%dx", &v); //Please consusme me
   writefln("[%s][%s]", v, s);
}
--------
[42][x42xT] //My range is unchanged
[42][T]     //My range was consumed
--------

I think this is a good solution. Do you see anything I may have 
failed to see?