Re: [Boost-users] [multi-index] No constructor that takes allocator only

From: Joaquín Mª López Muñoz (joaquin_at_[hidden])
Date: 2008-01-30 12:48:55

Michael Fawcett ha escrito:

> Joaquín, thanks so much for a wonderful library.  I was wondering why
> there is no constructor that simply takes an allocator.  This would
> make multi_index behave more like STD Library containers, which would
> aid me in allowing flexible storage options for generic algorithms.
>
> Is there a technical hurdle that makes this difficult to do?  You
> currently provide:
>
> explicit multi_index_container(
>     const ctor_args_list& args_list=ctor_args_list(),
>     const allocator_type& al=allocator_type());
>
> template<typename InputIterator>
> multi_index_container(
>     InputIterator first,InputIterator last,
>     const ctor_args_list& args_list=ctor_args_list(),
>     const allocator_type& al=allocator_type());
>
> Is it possible to also provide:
>
> explicit multi_index_container(
>     const allocator_type& al=allocator_type());
>
> ?

Hello Michael,

Not all STL containers provide an allocator ctor (associative containers don't),
which is the implicit reason why I didn't include it (I followed std::set's interface
in the initial designs). That said, I don't see any technical problem in providing
that ctor, so I'm putting it in my todo list for the next release (Boost 1.36, I'm
afraid).

Thanks for using Boost.MultiIndex,

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo