Re: [optional] Feedback on the range interface for Boost.Optional

From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2024-10-05 14:42:38

czw., 3 paź 2024 o 00:51 Vinnie Falco <vinnie.falco_at_[hidden]> napisał(a):

> On Mon, Sep 16, 2024 at 8:32 AM Steve Downey via Boost <
> boost_at_[hidden]> wrote:
>
>> ...
>
>
> For what it is worth, I rather like p3168r2 over the alternative. The
> design of ranges seems such that it anticipates an open set of library and
> user-defined adaptors, and long pipelines containing many small
> transformations to achieve a desired result. The `views::maybe` and
> `views::nullable` adaptors look very much like in the spirit of the ranges
> design: small, focused algorithms to achieve a specific well-defined
> purpose.
>
> p3168r2 claims that this:
>
>     // Compute eye colors of 'people'.
>     vector<string> eye_colors = people
>       | views::transform(&Person::eye_color)
>       | views::transform(views::nullable)
>       | views::join
>       | ranges::to<set>()
>       | ranges::to<vector>();
>
> is worse than this:
>
>     // Compute eye colors of 'people'.
>     vector<string> eye_colors = people
>       | views::transform(&Person::eye_color)
>       // no extra wrapping necessary
>       | views::join
>       | ranges::to<set>()
>       | ranges::to<vector>();
>
> I prefer the first one, since the transformation is explicit. p3168r2
> suggests that the new syntax is "dramatically more straightforward" which
> seems exaggerated to me. It is in fact less straightforward, as now the
> reader is expected to know about std::optional's expanded role as a range.
>
> I'm all for simplicity, but when you choose C++ you are opting in to a
> certain minimum level of complexity. views::maybe and views::nullable seem
> like just the right level of complexity for C++. A rangeful std::optional
> does not do much for me.
>

Ok, I now have a paper to revert the range interface from Optional:
https://isocpp.org/files/papers/D3415R0.html

Regards,
&rzej;