使用 std::bind 时从 std::function 获取函数指针

我正在尝试使用std::function和这个结合std::bind，但我遇到了一些问题。

这有效：

#include <functional>
#include <iostream>

void print() {
    std::cout << 2;
}

int main() {
    std::function<void ()> foo = print;
    (*foo.target<void (*)()>())(); //prints 3
}

这在第二行崩溃了main:

#include <functional>
#include <iostream>

void print (int i) {
    std::cout << i;
}

int main() {
    std::function<void ()> foo = std::bind (print, 2);
    (*foo.target<void (*)()>())();
}

我真的握着std::function<void ()>并且需要能够返回该函数；不只是称呼它。我预计用法会是这样的：

#include <functional>
#include <iostream>

void print (int i) {
    std::cout << i;
}

int main() {
    Container c (std::bind (print, 2));

    //I would expect the original
    c.func() (3); //prints 3

    if (c.func() == print) /* this is what I'm mostly getting at */
}

有什么方法可以让原始函数返回它，或者有替代方法吗？它也与返回类型发生冲突，因为void (*)()与绑定签名非常匹配。

This is quite impossible. The whole reason that std::function exists is that function pointers suck horrifically and should never, ever, be used by anyone, ever again, except for the doomed souls bearing the Burning Standards of Hell C interoperation, because they cannot handle functions with state.

A std::function<void()>在一般情况下，不能转换为void(*)()。这在第一个示例中起作用的唯一原因是因为它happens成为一个void(*)()起初。