Re: [Boost-users] Multi Index: Nested std::pair

Subject: Re: [Boost-users] Multi Index: Nested std::pair
From: Etienne Philip Pretorius (icewolfhunter_at_[hidden])
Date: 2009-04-26 19:55:05

>                 /*unique values per x co-ordinate*/
>                 boost::multi_index::ordered_non_unique<
>                     boost::multi_index::composite_key<
>                         element_t,
>                         boost::multi_index::member<
>                             element_t,
>                             unsigned char,
>                             &element_t::x
>                         >,
>                         boost::multi_index::member<
>                             element_t,
>                             unsigned char,
>                             &element_t::value
>                         >
>                     >
>                 >
>             >
>         > matrix_t;
> 
> How would I define the "unique values per x co-ordinate" as there x 
> co-ordinate is suppose to be non unique while value in this key should 
> ONLY point to unique instances within that x co-ordinate?
> 
Would this work?

                 /*unique values per x co-ordinate*/
                 boost::multi_index::ordered_unique<
                     boost::multi_index::composite_key<
                         element_t,
                         boost::multi_index::member<
                             element_t,
                             unsigned char,
                             &element_t::x
                         >,
                         boost::multi_index::member<
                             element_t,
                             unsigned char,
                             &element_t::value
                         >
                     >
                 >

As it is not clear in the documentation what the 
"boost::multi_index::ordered_unique" scope is. IE is it the combination 
of the defined members (member vs member) of is it based on the first 
and then on the second (first vs first, second vs second).

Etienne