Re: Does anybody know why boost::array does not support multiple dimensions?

From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2022-01-09 06:53:49

On Jan 8, 2022, at 9:46 PM, Helmut Zeisel via Boost <boost_at_[hidden]> wrote:
> 
>> Von: "Ivan Matek" <libbooze_at_[hidden]>
>> On Fri, Jan 7, 2022 at 8:16 AM Helmut Zeisel via Boost <boost_at_[hidden][mailto:boost_at_[hidden]]> wrote:
>>> 1) boost::multi_array_ref does not own the memory (which creates at least the memory overhead of one pointer)
>> AFAIK boost::multi_array (no _ref suffix)  owns memory, but it still does 1 heap allocation.
> 
> Yes.
> 
> What I have in mind, however, (as I mentioned already ealier) is some general adapter class
> 
> template<typename T, typename Index, typename Policy>
> struct array_index_adapter { ... };
> 
> that can apply different types of indices (row major, column major, triangular ...) to different containers (stack allocated, heap allocated, mixed like boost::small_vector etc).

You should look at mdspan, then.
It’s been in use at various national labs for many years, and is being proposed for a future standard.

A reference implementation is here: https://github.com/kokkos/mdspan

— Marshall