Re: [boost] C++11 Metaprogramming

Subject: Re: [boost] C++11 Metaprogramming
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2012-04-03 09:23:39

On 04/03/2012 01:14 PM, Dave Abrahams wrote:

> I don't understand what you mean by "them" in "expand them."

I meant template parameter packs.

> Argument
> packs can certainly be expanded in arguments to non-variadic templates.
> For example,
>
>    template<class...Ts>  struct vector {};
>    template<class Sequence>  struct non_variadic {};
>    template<class...Ts>  struct foo : non_variadic<vector<Ts...>  >  {};
>
> But I'm sure you knew that already.  The inability to handle argument
> packs directly without wrapping them in something like vector is a real
> limitation, though.

I meant the inability to do

template<class T0 = void, class T1 = void, class T2 = void>
struct mpl_vector {};

template<class... T>
struct c11_vector : mpl_vector<T...> {};

But apparently, this is now allowed.