Re: [boost] [mpl] Is there anyone working on mpl with variadic templates ?

Subject: Re: [boost] [mpl] Is there anyone working on mpl with variadic templates ?
From: Larry Evans (cppljevans_at_[hidden])
Date: 2009-10-20 07:45:42

On 10/20/09 05:18, luozhiyuan wrote:
> Is it possible that BOOST_MPL_LIMIT_/seq/_SIZE can be removed when we 
> have variadic templates ?

Yes.  Please see:

   http://article.gmane.org/gmane.comp.lib.boost.devel/194084

The compiler patch mentioned there how been applied:

   http://gcc.gnu.org/ml/gcc-patches/2009-10/msg00892.html

One thing missing is a variadic version of arg<I>.  What's
needed for that is some way to index the pack expansion.  IOW,

template<int Idx>
struct arg
{
     template<typename... Args>
     apply
     {
         typedef Args...[Idx] type;
     };
};

where Args...[Idx] returns the Idx-th type in the
pack expansion, Args....

Apparently there's some problem about how that can be
expressed unambiguously.  Search for "most-requested"
here:

http://groups.google.com/group/comp.std.c++/msg/40705c1e2a6f78f8

-regards,
Larry