求问c++11中function绑定类成员变量的问题

[zeqi1991]

#include <iostream>
#include <functional>
#include <string>

using namespace std;

class Foo
{
public:
    Foo();
    ~Foo();
    Foo(const Foo& other);
    Foo& operator = (const Foo& other);
public:
    void methodA();
    void methodB(int num);
    void methodC(string& name);
private:
    int number_;
};

Foo::Foo()
{
    number_ = 0;
}

Foo::~Foo()
{
    number_ = 100;
}

Foo::Foo(const Foo& other)
{
    number_ = other.number_;
}

Foo& Foo::operator = (const Foo& other)
{
    if (this == &other)
        return *this;
    number_ = other.number_;
    return *this;
}

void Foo::methodA()
{
    cout << __FUNCTION__ << endl;
    number_ = 1000;
}

void Foo::methodB(int num)
{
    cout << __FUNCTION__ << endl;
    number_ = 1000;
    cout << number_ + num << endl;
}

void Foo::methodC(string& name)
{
    cout << __FUNCTION__ << endl;
    cout << name << endl;
    number_ = 1000;
    cout << number_ << endl;
}

std::function<void()> functor;

int main()
{
    //foo后，为什么functor()还能正确执行
    //如果functor中被绑定的是一个copy的Foo对象，但是没有调用copy函数
    {
        Foo foo;
        functor = std::bind(&Foo::methodA, &foo);
    }
    functor();

    {
        Foo foo;
        functor = std::bind(&Foo::methodB, &foo, 100);
    }
    functor();

    {
        Foo foo;
        functor = std::bind(&Foo::methodC, &foo, string("Foo"));
    }
    functor();
    return 0;
}

[sdghchj]

栈上的对象虽然已经销毁，但原指针所指的内存块数据可能依然存在，这是不安全的代码，运行正常不等于正确。