Re: [Boost-users] [MultiIndex] more on key extractor issues

Subject: Re: [Boost-users] [MultiIndex] more on key extractor issues
From: Joaquin M Lopez Munoz (joaquin_at_[hidden])
Date: 2013-01-19 12:47:19

John M. Dlugosz <mpbecey7gu <at> snkmail.com> writes:

> 
> I think my problem stems from the use of 'const' in the underlying element
> with pointer 
> traversal.
> 
> Consider:
> 
> typedef multi_index_container<
>      shared_ptr< const ItemBase >,
>      indexed_by<
> 
>         ordered_non_unique<
>            member<
>               const ItemBase,  // <<--- here
>               const unsigned long,  // <<--- here
>               &ItemBase::some_member
>               >
>            >, // ordered_non_unique
> 
>         ordered_unique<
>            tag<S2>,
>            member<
>               ItemBase,
>               const S2,
>               &ItemBase::another_member
>               >
>            > // ordered_unique
> 
>         > // indexed_by
>      > ItemList_type_base;

Have you taken a look at the table in:

http://www.boost.org/libs/multi_index/doc/tutorial/
key_extraction.html#advanced_key_extractors

Regardless of whether the indexed-by member is const or not, when using
pointers to const elements the proper way of declaring the extractors is:

  member<
   ItemBase,
   const unsigned long,
   &ItemBase::some_member
  >

  member<
    ItemBase,
    const S2,
    &ItemBase::another_member
  >

This should clear problems away both in VS and Clang (please report
otherwise.)

Joaquín M López Muñoz
Telefónica Digital