Re: [Boost-users] Using an mpl sepquence as a template parameter

Subject: Re: [Boost-users] Using an mpl sepquence as a template parameter
From: Gabriel Redner (gredner_at_[hidden])
Date: 2011-11-14 17:00:01

Several times I've done something like this:

namespace detail {

struct none {};

template <typename TSeq>
struct strip_none
{
        typedef typename boost::mpl::remove<TSeq, none>::type type;
};

} // namespace detail

template <
  typename T0,
  typename T1 = detail::none, typename T2 = detail::none,
  typename T3 = detail::none, typename T4 = detail::none,
  typename T5 = detail::none, typename T6 = detail::none>
class some_class
{
  typedef boost::mpl::vector<T0, T1, T2, T3, T4, T5, T6> raw_types;
  typedef typename detail::strip_none<raw_types>::type types;
  ...
};

Presumably some simple PP magic could make this prettier.

-Gabe