重载一元运算符 & 是否有意义? [英] Does it ever make sense to overload unary operator &?

问题描述

因此，C++ 允许重载一元 operator &(address).当 operator & 正确重载时，您是否知道任何现实世界 示例?第二个更具体的问题是，您是否知道 operator & 在保留地址语义的同时正确重载的任何现实世界示例?TIA

So, C++ allows overloading the unary operator &(address). Are you aware of any real-world example when operator & was rightfully overloaded? And a second, more specific question, are you aware of any real-world example when operator & was rightfully overloaded while preserving address semantics? TIA

推荐答案

我有 207 个 真实世界 operator &() 示例:代码搜索 1, 代码搜索 2.

I've got 207 real-world examples of operator &(): Code search 1, Code search 2.

包括SafeInt<>(获取底层裸整数)，boost::gil(显然也是为了让步原始数据)，Mozilla(说定义操作符是有风险的，但是，嘿，我们知道我们在做什么.")，wxWidgets，Armagtron 等等.

Including SafeInt<> (to get the underlying naked integer), boost::gil (apparently also to yield the raw data), Mozilla (that say "it is risky to define operator&, but, hey, we know what we're doing."), wxWidgets, Armagetron and lots of more.

似乎有些人使用迭代器习语 &*it 来获取原始引用或向后的指针，并编写 *&it 来获取原始引用和 &it 获取原始指针.

It seems some use the iterator idiom &*it to get a raw reference or pointer backwards, and write *&it to get a raw reference and &it to get a raw pointer.

请注意，一旦您的类型重载 operator& 并返回与内置运算符不同的内容，您的类型就不再是 CopyConstructible(在 C++03 中 - C++0x 似乎已经解除it)，因此不能再用作标准容器中的元素类型.

Notice that once your type overloads operator& and returns something different than the built-in operator, your type is not CopyConstructible anymore (in C++03 - C++0x seems to have lifted it), and so cannot be used as element-type in a Standard container anymore.

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