compile-time opIndex

[Artur Skawina via Digitalmars-d]

On 12/18/14 16:43, Steven Schveighoffer via Digitalmars-d wrote:
> We currently have the ability to do opIndex for simulating an array or other type indexed at runtime.
> 
> But we have no way to simulate the ability of tuple indexing. Such an ability would unleash a huge amount of possibilities, including user-defined tuple types.

   struct TupleWannabe(S) {
      typeof(S.tupleof) tupleof;

      static __memberWannabe() {
         string s;
         foreach (I, _; typeof(S.tupleof))
            s ~= `ref `~S.tupleof[I].stringof~`() @property {
                     return tupleof[`~I.stringof~`];
                  } `;
         return s;
      }
      mixin(__memberWannabe());

      alias tupleof this;
   }
   
   struct S {
      int key;
      string val;
   }

   alias ST = TupleWannabe!S;

   void main() {
      ST s = ST(1, "blah");
      s.key = 2;
      s.val = "yada";
      s[0] = 42;
      s[1] = "etc";
   }

SCNR. Happy new year!

artur