instantiate each of a tuple of templates (Take 2)

[John Colvin]

On Thursday, 1 August 2013 at 15:06:50 UTC, Artur Skawina wrote:
> 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

sorry yeah I didnt think the question through before asking. I'm 
normally the one nagging for better example code when people ask 
questions!

I did consider wading through everything with string mixins etc. 
but it seemed like a lot of effort for what (on the surface) is a 
simple problem.

Anyhow, please see my response to monarch_dodra as I've revised 
my question somewhat