Re: How to add n items to TypeTuple?

[Simen Kjaeraas]

On 2012-11-01, 19:52, Justin Whear wrote:

On Thu, 01 Nov 2012 19:42:07 +0100, denizzzka wrote:
For example, adding 3 strings to type tuple t:

foreach( i; 0..2 )
  alias TypeTuple!( t, string ) t; // this is wrong code

and result should be:

TypeTuple!( string, string, string );

Use a recursive template.  Here's one that repeats a given type N times:

template Repeat(Type, size_t Times)
{
    static if (Times == 0)
        alias TypeTuple!() Repeat;
    else
        alias TypeTuple!(Type, Repeat!(Type, Times - 1)) Repeat;
}

Invoke like so:
Repeat!(string, 3) threeStrings;

I've always preferred the opposite order of arguments, as that
allows repetition of more complex things:

template Repeat(size_t times, T...) {
    static if ( times == 0 ) {
        alias TypeTuple!() Repeat;
    } else {
        alias TypeTuple!( T, Repeat!( times - 1, T ) ) Repeat;
    }
}

Invoke like so:

alias Repeat!(4, string, int, "Hello, template world!")  
YeahThisIsGonnaBeUseful;

Or:

alias Repeat!(3, string) ThreeStrings;

--
Simen