std::function::target (3) Linux Manual Page

std::function<R(Args…)>::target – std::function<R(Args…)>::target

Synopsis

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)

Return value

A pointer to the stored function if target_type() == typeid(T), otherwise a null pointer.

Example

// 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

See also

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