GH-50250: [C++] Remove call_traits::argument_type in favor of <type_traits> - #51328
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GH-50250: [C++] Remove call_traits::argument_type in favor of <type_traits>#51328taepper wants to merge 1 commit into
call_traits::argument_type in favor of <type_traits>#51328taepper wants to merge 1 commit into
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pitrou
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Sep 14, 2026
| std::make_shared<Memoizer>(std::forward<Func>(func), cache_capacity)}; | ||
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| return shared_memoized; | ||
| return std::function<RetType(const Key&)>(std::move(shared_memoized)); |
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Wrapping the result in a std::function adds a layer of indirection when calling operator() that might be expensive. Can we avoid this?
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Unfortunately we'll have to wait for #51326 before we can ensure that this doesn't break on some C++ compilers on our CI platforms. |
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Rationale for this change
This is the last change for #50250. The remaining
FnOncedoes not have corresponding utilities in the C++20 standard library according to my knowledge.What changes are included in this PR?
This removes the custom meta-programming facility
call_traits::argument_type. We instead use the providedtype_traitsheader which allows us to check invocability (and thus indirectly the argument type) with e.g.std::is_invocable.It needs to be mentioned that none of
std::is_invocable_v,std::invoke_result_t, .. is a drop-in replacement for the removedargument_type. I instead migrated all users of the old facility to the standard constructs. Some call-sites needed changing by supplying template parameters explicitly, but in my opinion all changes are defendable or even improvements.Are these changes tested?
Yes, this refactoring commit still passes all test cases
Are there any user-facing changes?
No
arrow/util/functional.h#50250