Googlyeyecode

#include <functional>
#include <iostream>

struct Receiver {
    void receive(std::function<void()> f) {
        func_ = f;
    }
    std::function<void()> func_;
};

void pusher(Receiver& r) {
    auto wrapper=[&](std::function<void()> w) {
        r.receive([w=move(w)]() {
           std::cout << "Before" << std::endl;
           w();
           std::cout << "After" << std::endl;
        });
    };


    wrapper([&]() {
        std::cout << "Original" << std::endl;
    });
}

int x= 15;
int main() {
    std::function<void()>  a = [&]() {  std::cout << x << std::endl; };
    a();
    x = 20;
    a();

    Receiver r;
    pusher(r);
    r.func_();
    return 0;
}