Re: 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.