taepper commented on code in PR #50714:
URL: https://github.com/apache/arrow/pull/50714#discussion_r3676479493
##########
cpp/src/arrow/util/iterator.h:
##########
@@ -520,12 +517,11 @@ struct FilterIterator {
};
/// \brief Like MapIterator, but where the function can fail or reject
elements.
-template <
- typename Fn, typename From = typename
internal::call_traits::argument_type<0, Fn>,
- typename Ret = typename internal::call_traits::return_type<Fn>::ValueType,
- typename To = typename std::tuple_element<0, Ret>::type,
- typename Enable = typename std::enable_if<std::is_same<
- typename std::tuple_element<1, Ret>::type,
FilterIterator::Action>::value>::type>
+template <typename Fn, typename From,
+ typename Ret = typename std::invoke_result_t<Fn&, From>::ValueType,
+ typename To = std::tuple_element_t<0, Ret>,
+ typename Enable = std::enable_if_t<
Review Comment:
This is a very good point, I fixed this locally:
```diff
commit cc9f4df1a0423d67fa61337fb013e11cf71df417 (HEAD ->
minimize-functional-metaprogramming)
Author: Alexander Taepper <[email protected]>
Date: Wed Jul 29 19:05:30 2026 +0200
replace another `typename Enable` with `requires`
diff --git a/cpp/src/arrow/util/iterator.h b/cpp/src/arrow/util/iterator.h
index 3a098b1455..1ebdf1bb0c 100644
--- a/cpp/src/arrow/util/iterator.h
+++ b/cpp/src/arrow/util/iterator.h
@@ -518,10 +518,9 @@ struct FilterIterator {
/// \brief Like MapIterator, but where the function can fail or reject
elements.
template <typename Fn, typename From,
- typename Ret = typename std::invoke_result_t<Fn&,
From>::ValueType,
- typename To = std::tuple_element_t<0, Ret>,
- typename Enable = std::enable_if_t<
- std::is_same_v<std::tuple_element_t<1, Ret>,
FilterIterator::Action>>>
+ typename Ret = std::invoke_result_t<Fn&, From>::ValueType,
+ typename To = std::tuple_element_t<0, Ret>>
+ requires std::is_same_v<std::tuple_element_t<1, Ret>,
FilterIterator::Action>
Iterator<To> MakeFilterIterator(Fn filter, Iterator<From> it) {
return Iterator<To>(
FilterIterator::Impl<Fn, From, To>(std::move(filter), std::move(it)));
```
Is it okay to push these changes @pitrou ? I can also do this in the second
part of #50250 instead.
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