C++ 闭包捕获变量

问：

在 Cow（） 函数中。我正在尝试捕获闭合的可变重量。但它不能正常工作。可变重量不会捕获到瓶盖上。当我尝试运行getWeight（）函数时。它返回一个未初始化的值。此外，setWeight（） 不起作用。

#include <iostream>

struct Mammal {
  std::function<void()> speak;
  std::function<int()> getWeight;
  std::function<void(int)> setWeight;
};

Mammal *Cow() {
    int weight = 100;

    auto *m = new Mammal();
    m->speak = []() { puts("momo~~ momo~~"); };
    m->getWeight = [&]() { return weight; };;
    m->setWeight = [&](int w) { weight = w; };

    return m;
}

int main() {
    Mammal *c = Cow();
    std::cout << "Cow Weight: " << c->getWeight() << '\n';

    c->setWeight(200);
    std::cout << "Cow New Weight: " << c->getWeight() << '\n';
}