instantiate each of a tuple of templates (Take 2)

[Artur Skawina]

On 08/01/13 14:50, John Colvin wrote:
> template a(T ...)
> {
>     void a(R r)
>     {
>         //want to get a tuple of
>         //the members of T, each
>         //instantiated with R.
> 
>         //do some RT stuff
>     }
> }
> 
> Is this possible?
> 
> Whatever I try, I keep running in to "cannot use local as parameter to non-global template" errors, which I understand is to do with context pointers
> However, this is all compile-time work based entirely on types, there should be no need for any context pointers.
> 

Always post real and complete (even if not working) code, as figuring out
what the problem is can be harder than giving the solution...


   template RealTuple(A...) { alias RealTuple = A; }
   template a(T ...)
   {
       auto a(R)(R r)
       {
           //want to get a tuple of
           //the members of T, each
           //instantiated with R.

           mixin({
              string m;
              foreach (I, _; T)
                 m ~= "alias UGH"~I.stringof~" = T["~I.stringof~"];\n";
              m ~= "alias TupleofTsBangR = RealTuple!(";
              foreach (I, _; T)
                 m ~= (I?", ":"") ~ "UGH"~I.stringof~"!R";
              return m ~ ");";
           }());

           // do some RT stuff

           TupleofTsBangR x;
           foreach (I, _; typeof(x))
               x[I] = r;

           // etc

           import std.typecons;
           return tuple(x);
       }
   }

(If this is what you were actually looking for then I hope somebody
 else has another solution; this approach is just too ugly...)

artur