Re: Multiple return values...

[Derek]

On Thu, 15 Mar 2012 19:23:57 +1100, Timon Gehr <timon.g...@gmx.ch> wrote:

I'd like to break the nexus between science and magic here.

// this is used to access language built-in tuples
template to(T...) {
     alias T to;
}

// this builds a struct akin to std.typecons.tuple
// it contains the function parameters as fields t[0], t[1],...
auto from(T...)(T t) {
     struct Result { T t; alias t this; }
     return Result( t );
}

// to!(a,b) creates a tuple containing aliases to a and b

to!(a,b) = from(b,a);   // cannot assign Result to two fields
to!(a,b) = from(b,a).t; // try alias this
auto __tmp = from(b,a).t; // expand tuple assign to multiple assignment
a[0] = __tmp[0], a[1] = __tmp[1];

Thanks, but I was hoping more for an explanation in English.

Are you saying that the generated code is something like ...

   struct __tmpS { int Fa, int Fb };
   __tempS __tmp;
   __tmp.Fa = a;
   __tmp.Fb = b;
   a = __tmp.Fb;
   b = __tmp.Fa;


--
Derek Parnell
Melbourne, Australia