How to mixin each element of tuple

[Timon Gehr]

On 12/20/2011 02:32 PM, Michal Minich wrote:
> My naive approach doesn't works
>
> struct Item1 (T) {}
> struct Item2 (T) {}
>
> struct Group (Items ...)
> {
>      // how to do this? ... no static foreach :(
>      static foreach (I; Items)
>          mixin I!(int);
> }
>
>
> void main ()
> {
>      alias Group!(Item1, Item2) G;
> }

This will do what you want:

Solution 1:

struct Item1(T){}
struct Item2(T){}

mixin template getItems(Items ...){
     static if(Items.length) {
         private alias Items[0] _item;
         mixin _item!int;
         mixin getItems!(Items[1..$]);
     }
}

struct Group(Items...)
{
     mixin getItems!Items;
}

void main(){
     alias Group!(Item1, Item2) G;
}


Solution 2:

struct Item1(T){}
struct Item2(T){}

struct Group(Items...) {
     private static string gen(){
         string r;
         foreach(i;0..Items.length){
             import std.conv;
             r~=`private alias Items[`~text(i)~`] _item`~text(i)~`;`;
             r~=`mixin _item`~text(i)~`!int;`;
         }
         return r;
     }
     mixin(gen());
}

void main(){
     alias Group!(Item1, Item2) G;
}

But I'd rather have static foreach too.