operator ->重载是怎么做到的?

https://stackoverflow.com/questions/8777845/overloading-member-access-operators-c

struct client

    { int a; };

struct proxy {

    client *target;

    client *operator->() const

        { return target; }

};

struct proxy2 {

    proxy *target;

    proxy &operator->() const

        { return * target; }

};

void f() {

    client x = { 3 };

    proxy y = { & x };

    proxy2 z = { & y };

    std

并非如普通操作符一样在class内部定义一个函数做重载,而是通过一个代理类.