Re: [Boost-users] [bind] Possible to use variadic templates with bind?

Subject: Re: [Boost-users] [bind] Possible to use variadic templates with bind?
From: Larry Evans (cppljevans_at_[hidden])
Date: 2010-07-21 14:41:29

On 07/21/10 11:23, Peter Dimov wrote:
[snip]
> An interesting puzzle. I tried to apply the 'Indexes' technique shown in 
> the bind implementation section of
> 
> http://osl.iu.edu/~dgregor/cpp/variadic-templates.pdf
> 
> and ended up with the following:
> 
> #include <boost/bind.hpp>
> #include <boost/function.hpp>
> 
> template<int...> struct int_tuple {};
> 
> // make indexes impl is a helper for make indexes
> template<int I, typename IntTuple, typename... Types>
> struct make_indexes_impl;
> 
> template<int I, int... Indexes, typename T, typename... Types>
> struct make_indexes_impl<I, int_tuple<Indexes...>, T, Types...>
> {
>    typedef typename make_indexes_impl<I+1,
>        int_tuple<Indexes..., I>,
>        Types...>::type type;
> };
> 
> template<int I, int... Indexes>
> struct make_indexes_impl<I, int_tuple<Indexes...> >
> {
>    typedef int_tuple<Indexes...> type;
> };
> 
> template<typename... Types>
> struct make_indexes: make_indexes_impl<0, int_tuple<>, Types...> { };
[snip]
That make_indexes was the inspiration for:

http://svn.boost.org/svn/boost/sandbox/variadic_templates/boost/mpl/package_range_c.hpp

One additional feature of package_range_c is the the order of the
indexes can be reversed.  Useful if you want to reverse the order
of a mpl sequence.

-regards,
Larry