Re: [boost] [multi_index] Taking advantage of C++17 auto template params to simplify key specification

On Wed, Sep 27, 2017 at 12:53 PM, Joaquin M López Muñoz via Boost < boost@lists.boost.org> wrote:

using container=multi_index_container< element, indexed_by< ordered_unique>, ordered_unique>, ordered_unique> >

...

;

classical def#1

With the advent in C++17 of auto non-type template parameters, it is very easy to provide a boost::multi_index::key class template so that we can write:

using container=multi_index_container< element, indexed_by< ordered_unique>, ordered_unique>, ordered_unique> >

...

;

C++17 def#2

(Example at http://coliru.stacked-crooked.com/a/5742c768cc093c03 ).

template<auto Member> struct key{}; template struct key<PtrToMember>: boost::multi_index::member{}; template struct key<PtrToMemberFunction>: boost::multi_index::const_mem_fun{}; template struct key<PtrToMemberFunction>: boost::multi_index::mem_fun{}; template struct key<PtrToFunction>: boost::multi_index::global_fun{}; Is there interest in adding this to Boost.MultiIndex? Comments on this

[...] syntaxes?

I'm out of my depth here, but the fact you use inheritance means the two types are not the same as a consequence, right? I.e. std::is_name is false? And I suppose such partial specialization is not possible with template type aliases to have is_same<> being true? Not sure it matters, just thinking out loud. --DD