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

Subject: Re: [boost] [multi_index] Taking advantage of C++17 auto template params to simplify key specification
From: Richard Hodges (hodges.r_at_[hidden])
Date: 2017-09-27 11:29:12

Definitely interesting to me. Also key_tuple<...> which would automatically
tie a number of elements?

On 27 September 2017 at 13:23, Andrey Semashev via Boost <
boost_at_[hidden]> wrote:

> On 09/27/17 13:53, Joaquin M López Muñoz via Boost wrote:
>
>> Consider the following:
>>
>>    struct element
>>    {
>>      int x;
>>      int f()const{return x;}
>>    };
>>
>>    int gf(const element& e){return e.x;}
>>
>>    using container=multi_index_container<
>>      element,
>>      indexed_by<
>> ordered_unique<member<element,int,&element::x>>,
>> ordered_unique<const_mem_fun<element,int,&element::f>>,
>>        ordered_unique<global_fun<const element&,int,&gf>>
>>      >
>>    >;
>>
>> 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<key<&element::x>>,
>>        ordered_unique<key<&element::f>>,
>>        ordered_unique<key<&gf>>
>>      >
>>    >;
>>
>> (Example at http://coliru.stacked-crooked.com/a/5742c768cc093c03 ).
>>
>> Is there interest in adding this to Boost.MultiIndex? Comments on this or
>> alternative syntaxes?
>>
>
> Looks interesting. The C++03 version always seemed verbose to me. Will it
> also support function objects for key extraction?
>
>
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