std::addressof - 奇怪的实现 [英] std::addressof - strange implementation

问题描述

所以几天前我了解了 std::addressof.在 http://en.cppreference.com/w/cpp/memory/addressof 一个可能的实现是给定:

So a few days ago i learned about std::addressof. At http://en.cppreference.com/w/cpp/memory/addressof a possible implementation is given:

template< class T >
T* addressof(T& arg) 
{
    return reinterpret_cast<T*>(
               &const_cast<char&>(
                  reinterpret_cast<const volatile char&>(arg)));
}

据我所知，这可以简单地实现如下:

As far i see this can simply be implemented like:

template<typename T>
T* addressof( T& var )
{
    return &var;
}

为什么 cppreference 的人选择用 3 个强制转换来实现它?是否有任何我遗漏的细节使他们的实施更好.当您所做的只是强制转换时，使用 volatile 有什么意义?

Why the guys at cppreference chose to implement it with 3 casts? Is there any detail I am missing that is making their implementation better. What is the point in using volatile when all you do is cast?

推荐答案

如果它可以像你的例子那样实现，就没有必要了.关键是它为您提供了对象的地址，即使该类型的 operator& 的地址已被重载.

If it could be implemented like in your example, there would be no need for it. The point is that it gives you the address of an object, even if the address-of operator& for that type has been overloaded.

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