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Re: [std-proposals] Defect report for std::apply (or apply_perfectly)

From: Frederick Virchanza Gotham <cauldwell.thomas_at_[hidden]>
Date: Mon, 11 Mar 2024 10:26:10 +0000
On Mon, Mar 11, 2024 at 10:07 AM Frederick Virchanza Gotham wrote:
> Although maybe I could have written a lambda or a template class to do
> away with the preprocessor macroes.

Here it is without the preprocessor macroes:

    template<typename Tuple, size_t I>
    class CastTo final {
        using tElem = tuple_element_t< I, remove_reference_t<Tuple> >;
        using tElem_NoRef = remove_reference_t<tElem>;
        inline static constexpr bool vElem_IsRef =
        inline static constexpr bool vElem_ShouldBeR =
is_rvalue_reference_v<tElem> || (!vElem_IsRef &&
        using type = conditional_t< vElem_ShouldBeR , tElem_NoRef&&,
tElem_NoRef& >;

    template<typename Tuple, size_t I>
    using CastTo_t = CastTo<Tuple,I>::type;

    template<typename F, typename Tuple, size_t... I>
    constexpr decltype(auto) apply_perfectly_impl(F &&f, Tuple &&t,
        return invoke( forward<F>(f), static_cast< CastTo_t<Tuple,I>
>( get<I>(t) )... );

I've left out the 'noexcept(noexcept(................))' on both
functions because it's so long.

Received on 2024-03-11 10:26:19