std::function::target
template< class T > T* target(); | (1) | (since C++11) |
|---|---|---|
template< class T > const T* target() const; | (2) | (since C++11) |
返回指向存储的可调用函数目标的指针。
参数
%280%29
返回值
指向存储函数的指针target_type() == typeid(T)，否则为空指针。
例外
noexcept规格：
noexcept
例
二次
#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));
}二次
产出：
二次
test function: it is plus
test function: it is minus
test function: it is the function f
test function: it is the function g二次
另见
target_type | obtains the typeid of the stored target (public member function) |
|---|
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