syntax for calling to with a getter as source argument

[Klb via Digitalmars-d-learn]

On Tuesday, 15 July 2014 at 00:19:15 UTC, Ali Çehreli wrote:
> On 07/14/2014 05:10 PM, Ali Çehreli wrote:
>
> > On 07/14/2014 04:04 PM, H. S. Teoh via Digitalmars-d-learn
> wrote:
> >
> >  > On Mon, Jul 14, 2014 at 09:12:30PM +0000, Klb via
> Digitalmars-d-learn
> > wrote:
> >  >> hello what is the right syntax for this:
> >  >>
> >  >> ----------------------------------------------------
> >  >> import std.stdio, std.conv;
> >  >>
> >  >> void main(string args[])
> >  >> {
> >  >>      ubyte[3] src = [0, 1, 2];
> >  >>      string trg = "";
> >  >>
> >  >>      @property ubyte[3] srcAsProp(){return src;}
> >  >>
> >  >>      // Error: template std.conv.to cannot deduce
> function from
> > argument types
> >  >>      // !(string)(ubyte[3]), candidates are:
> >  >>      trg = to!(string)(srcAsProp());
> >  >> }
> >  >> ----------------------------------------------------
> >  >>
> >  >> In a real-world application I'd use an intermediate value
> but I'd like
> >  >> to know If it's possible...The strange fact is that it
> doesn't trig an
> >  >> error if src is a dyn. array. (if you remove the 3 from
> [3] then it
> >  >> passes).
> >  >
> >  > You need to slice the static array:
> >  >
> >  >     trg = to!string(srcAsProp()[]);
> >
> > There seems to be an attempt in Phobos to support it without
> needing an
> > explicit slice.
> >
> >  From std/phobos/conv.d:
>
> I meant phobos/std/conv.d there.
>
> > /*
> >    Converting static arrays forwards to their dynamic
> counterparts.
> >   */
> > T toImpl(T, S)(ref S s)
> >      if (isRawStaticArray!S)
>
> Ok, I think I see now (after two minutes after posting it :) ) 
> why it doesn't work. The overload above takes by-ref, which 
> does not bind to rvalues in D.
>
> And the problem is, what srcAsProp() returns is an rvalue 
> because static arrays are value-types and they get copied.
>
> > {
> >      return toImpl!(T, typeof(s[0])[])(s);
> > }
> >
> > @safe pure nothrow unittest
> > {
> >      char[4] test = ['a', 'b', 'c', 'd'];
> >      static assert(!isInputRange!(Unqual!(char[4])));
> >      assert(to!string(test) == test);
> > }
> >
> > I don't know why that overload does not take care of OP's
> case. (I am be
> > completely off here. :) )
>
> I hope I have it now. :p
>
> Ali

Thanks for this accurate explanation. The problem is quite clear 
now.