On 12/12/2021 21.00, Barry Revzin wrote:
>
>
> On Sun, Dec 12, 2021 at 4:30 AM Jens Maurer <Jens.Maurer_at_[hidden] <mailto:Jens.Maurer_at_[hidden]>> wrote:
>
> On 11/12/2021 23.00, Victor Zverovich via SG16 wrote:
> > Hi Tom and other Unicoders,
> >
> > Can we review an updated revision of P2286 (https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html <https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html> <https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html <https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html>>) during the upcoming meeting since there is still chance that it can target C++23? This revision addresses the SG16 feedback, particularly around escaping (https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html#escaping-behavior <https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html#escaping-behavior> <https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html#escaping-behavior <https://brevzin.github.io/cpp_proposals/2286_fmt_ranges/p2286r4.html#escaping-behavior>>). I think it's way more important and time sensitive than LWG issues related to fill.
>
> Why do we need a
>
> range_formatter
> and
> tuple_formatter ?
>
> Isn't it enough that the standard library provides partial
> specializations of formatter<T> to offer the functionality?
>
> Jens
>
>
> Fewer template instantiations, and users can use range_formatter<int> to help them format any range of ints if they want to do something internally themselves.

But that range of ints will match formatter<R>, too, I guess?
If formatter<R> derives from range_formatter<range_reference_t<R>>,
using a formatter<R> seems to also instantiate range_formatter.
If the latter doesn't exist, those template instantiations are
saved.

> It's just more user friendly. They can use formatter<R> if they really want to too, this is just more direct.

I don't understand.

Could you point me to a section in the paper that specifically
addresses that having both range_formatter<V> and a partial
specialization for formatter<R> is "more user-friendly"?
I thought those formatters were intended as helpers for
std::format, anyway?

Jens