Setting defaults to variadic template args

[luka8088]

Or maybe... This seems like a much better solution:


module program;

import std.stdio;
import std.traits;
import std.typetuple;

template SelectTrue (bool condition, T) {
   static if (condition)
     alias T SelectTrue;
}

struct Event (T...) {

   alias TypeTuple!(T,
     SelectTrue!(T.length < 1, int),
     SelectTrue!(T.length < 2, float),
   ) T2;

   void F (T2 args) {
     writeln(typeid(typeof(args)));
   }

}

void main () {

   Event!() e1;

   e1.F(5, 6);

}



On Tuesday, 2 October 2012 at 13:44:10 UTC, luka8088 wrote:
>
> module program;
>
> import std.stdio;
> import std.traits;
> import std.typetuple;
>
> struct Event (T...) {
>
>   alias EraseAll!(void, TypeTuple!(T,
>     Select!(T.length < 1, int, void),
>     Select!(T.length < 2, float, void),
>   )) T2;
>
>   void F (T2 args) {
>     writeln(typeid(typeof(args)));
>   }
>
> }
>
> void main () {
>
>   Event!() e1;
>
>   e1.F(5, 6);
>
> }
>
>
> On Tuesday, 2 October 2012 at 13:15:08 UTC, Manu wrote:
>> Is it possible?
>>
>> Eg:
>>  struct Event(T... = (int, float))
>>  {
>>    void F(T...); // <- should default to F(int, float)
>>  }
>>
>> Does anyone have any clever tricks that will work in this 
>> scenario? Some
>> magic tuple syntax?