std::function::target(3)

💅 std::function::target(3) 💅

okay bestie, this is the page for std::function::target(3) from the C++ Standard Libary — yes, that’s the manual name, we’re keeping it exactly as it is, no cap 💅. It’s giving “niche C++ member function but make it a vibe check.” Let’s go.

✨ NAME ✨

std::function::target — std::function::target. literally that. iconic. periodt.

✨ Synopsis ✨

Both overloads are since C++11, fr fr:

template< class T >               (1) (since C++11)
T* target() noexcept;
template< class T >               (2) (since C++11)
const T* target() const noexcept;

Returns a pointer to the stored callable function target.

🌸 Parameters 🌸

None. (none) — no parameters, bestie 🫶.

💖 Return value 💖

A pointer to the stored function if target_type() == typeid(T), otherwise a null pointer. That’s the whole return vibe.

🎀 Example 🎀

okay so here’s the code, copied exactly because we do not mess with code in this house 🫶:

// Run this code

#include <functional>
#include <iostream>

int f(int, int) { return 1; }
int g(int, int) { return 2; }
void test(std::function<int(int, int)> const& arg)
{
    std::cout << "test function: ";
    if (arg.target<std::plus<int>>())
        std::cout << "it is plus\n";
    if (arg.target<std::minus<int>>())
        std::cout << "it is minus\n";

    int (*const* ptr)(int, int) = arg.target<int(*)(int, int)>();
    if (ptr && *ptr == f)
        std::cout << "it is the function f\n";
    if (ptr && *ptr == g)
        std::cout << "it is the function g\n";
}

int main()
{
    test(std::function<int(int, int)>(std::plus<int>()));
    test(std::function<int(int, int)>(std::minus<int>()));
    test(std::function<int(int, int)>(f));
    test(std::function<int(int, int)>(g));
}

🍓 Output 🍓

test function: it is plus
test function: it is minus
test function: it is the function f
test function: it is the function g

💀 Defect reports 💀

The following behavior-changing defect reports were applied retroactively to previously published C++ standards. ngl, retroactive lore drop.

• DR: LWG 2591
  • Applied to: C++11
  • Behavior as published: the behavior is undefined if T is not Callable
  • Correct behavior: behavior is defined (always returns nullptr)

🌈 See also 🌈

• target_type — obtains the typeid of the stored target (public member function).

okay that’s the whole page, bestie 💖 source/version: http://cppreference.com · date: 2024.06.10 · periodt. 🫶