NAME¶

std::indirect_result_t - std::indirect_result_t

Synopsis¶

Defined in header <iterator>
template< class F, class... Is >

requires (std::indirectly_readable<Is> && ...) &&
std::invocable<F, std::iter_reference_t<Is>...> (since C++20)

using indirect_result_t = std::invoke_result_t<F,
std::iter_reference_t<Is>...>;

The alias template indirect_result_t obtains the result type of invoking an
invocable type F on the result of dereferencing indirectly_readable types Is....

Template parameters¶

F - an invocable type
Is - indirectly readable types that are dereferenced to arguments

Example¶

// Run this code

#include <iterator>
#include <type_traits>

struct Fn
{
long operator()(const int&);
int operator()(int&&);
short operator()(int, int) const;
auto operator()(const float) -> int&;
void operator()(int[8]);
};

static_assert(
std::is_same_v<std::indirect_result_t<Fn, const int*>, long> and
std::is_same_v<std::indirect_result_t<Fn, std::move_iterator<int*>>, int> and
std::is_same_v<std::indirect_result_t<const Fn, int*, int*>, short> and
std::is_same_v<std::indirect_result_t<Fn, float*>, int&> and
std::is_same_v<std::indirect_result_t<Fn, int**>, void>
);

int main() {}

See also¶

result_of deduces the result type of invoking a callable object with
invoke_result a set of arguments
(C++11)(removed in C++20) (class template)
(C++17)