C++23's range_adaptor_closure equivalent

[stripe2933]

Hello, is there any equivalent for C++23's range_adaptor_closure? It would be good to make user defined class inherits its CTRP parent so that reduce boilerplate for operator|.

[brevzin]

range-v3 has one, it just looks a little different. You can see the description in the paper.

Basically you write:

namespace ranges::views {
  struct join_view_fn {
    template <viewable_range R>
        requires /* ... */
    constexpr auto operator(R&& r)
        -> join_view<all_t<R>>;
  };

  // for user consumption
  inline constexpr view_closure<join_view_fn> join{};
}

instead of:

namespace ranges::views {
  struct join_view_fn : range_adaptor_closure<join_view_fn> {
    template <viewable_range R>
        requires /* ... */
    constexpr auto operator(R&& r)
        -> join_view<all_t<R>>;
  };

  // for user consumption
  inline constexpr join_view_fn join{};
}

[stripe2933]

Thank you for your answer.