>
> Would be better that instead of type alias use template variable?
> Then code will look more clean:
>
> ```
> //paper version:
> mdspan ms(p, integral_c<3>{}, 42, integral_c<5>{});
>
>
> //bit streamlined version:
> template<auto I>
> std::integral_constant<decltype(I), I> integral_c = {};
>
> mdspan ms(p, integral_c<3>, 42, integral_c<5>);
> ```
>

That's a very good point! it omits annoying brackets IMO.

probably name could be even shortened like:

```
> std::mdspan ms(p, std::c<3>, 42, std::c<5>);
> ```

My initial idea was to name it `std::constant`, but this seems to imply
that such NTTP can be non-integral such as `pair<int, int>`.
Although this is completely feasible, it seems to deviate from the original
intention of the paper.
I think just calling it `std::c` seems too shorthand, but I'm still open
for better naming.
Not too sure about the status of P2781 `std::constexpr_t`
<https://github.com/cplusplus/papers/issues/1458>, maybe this can be left
entirely to it.

Thanks agian for the valuable advice.

Hewill


Marcin Jaczewski <marcinjaczewski86_at_[hidden]> 於 2023年10月18日 週三 上午4:41寫道：

> wt., 17 paź 2023 o 05:41 Hewill Kang via Std-Proposals
> <std-proposals_at_[hidden]> napisał(a):
> >
> > Hi fellow experts,
> >
> > I wrote a paper based on this thread:
> >
> >
> https://htmlpreview.github.io/?https://github.com/hewillk/mdspan-ctad/blob/main/mdspan-ctad.html
> >
> > It is still in the draft stage so there may be parts that need to be
> considered. Any comments are welcome.
> >
> > Hewill
> >
> >
> > Hewill Kang <hewillk_at_[hidden]> 於 2023年10月5日 週四 下午3:21寫道：
> >>
> >> Hi fellow experts
> >>
> >> I initially thought that
> >>
> >> mdspan ms(ptr, integral_constant<size_t, 2>{},
> integral_constant<size_t, 6>{});
> >>
> >> would be deduced into mdspan<int, extents<size_t, 2, 6>>. However, as
> the current wording ([mdspan.mdspan.overview]), it is just mdspan<int,
> extents<size_t, dynamic_extent, dynamic_extent>>
> >>
> >> template<class ElementType, class... Integrals>
> >> requires((is_convertible_v<Integrals, size_t> && ...) &&
> sizeof...(Integrals) > 0)
> >> explicit mdspan(ElementType*, Integrals...)
> >> -> mdspan<ElementType, dextents<size_t, sizeof...(Integrals)>>;
> >>
> >> I wonder, is it a more appropriate choice to set the corresponding
> extents's static values based on whether Integrals... is integral_constant?
> For example
> >>
> >> mdspan ms(ptr, integral_constant<size_t, 2>{},
> >> integral_constant<size_t, 3>{},
> >> 4,
> >> integral_constant<size_t, 5>{});
> >>
> >> which will be deduced as mdspan<int, extents<size_t, 2, 3,
> dynamic_extent, 5>>.
> >>
> >> What do you guys think? Could this be considered an improvement?
> >>
> >> Hewill
>
> Would be better that instead of type alias use template variable?
> Then code will look more clean:
>
> ```
> //paper version:
> mdspan ms(p, integral_c<3>{}, 42, integral_c<5>{});
>
>
> //bit streamlined version:
> template<auto I>
> std::integral_constant<decltype(I), I> integral_c = {};
>
> mdspan ms(p, integral_c<3>, 42, integral_c<5>);
> ```
> probably name could be even shortened like:
>
> ```
> std::mdspan ms(p, std::c<3>, 42, std::c<5>);
> ```
>
> another option is user defined literals but there
> is problem for good suffix as many are already
> used or could conflict with hex numbers (like suffix `c`).
>
>
> >
> > --
> > Std-Proposals mailing list
> > Std-Proposals_at_[hidden]
> > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>