Typed variadic template syntax?

[Andrei Alexandrescu]

On 1/28/14 4:14 PM, bearophile wrote:
> This is not an enhancement request, but it presents a potential
> enhancement.
>
>
> This is C++11 code:
>
> template<int... digits> struct value;
>
> template<> struct value<> {
>      static const int v = 0;
> };
>
> template<int first, int... rest> struct value<first, rest...> {
>      static int const v = 10 * value<rest...>::v + first;
> };
>
>
>
> You can translate it to D like this:
>
>
> enum isInt(T) = is(T == int);
>
> template value(xs...) if (allSatisfy!(isInt, xs)) {
>      static if (xs.length == 0)
>          enum value = 0;
>      else
>          enum value = xs[0] + 10 * value!(xs[1 .. $]);
> }

int value(int xs[]...) {
   int result = 0;
   foreach (i; xs) {
	result += 10 * result + i;
   }
   return result;
}

unittest
{
   static assert(value(1, 2) == 21);
}


Andrei