Building a compile time list incrementally in C++

Question

In C++, is there a way to build a compile time list incrementally, in the following pattern?

START_LIST(List)
ADD_TO_LIST(List, int)
ADD_TO_LIST(List, float)         


        

Answer 1

You could use C++11 variadic templates directly, they allow to write typelists in a much more fancy way than the classic functional head:tail approach:

template
struct list{};

using l = list;

On the other hand, if you like the head-tail way you could translate from one format to the other. In this case (Variadic to functional):

template
struct list{};

struct nil{};

template
struct make_list;

template
struct make_list
{
    using result = list::result;
};

template<>
struct make_list<>
{
    using result = nil;
};

An example:

//l is list>>
using l = typename make_list::result;

Of course you could use template aliases to make the syntax more clear:

template
using make = typename make_list::result;

using l = make;