如何在Rust中超载分配操作? [英] How can I overload the assignment operation in Rust?

问题描述

std::ops 中有很多操作，但是对于简单的任务来说什么都不是.

There are lots of operations in std::ops, but there is nothing for a simple assignment.

我来自C ++背景，那里有复制构造函数和赋值运算符重载，它们可以为您完成工作.我在Rust中需要类似的东西.

I'm coming from a C++ background, where there are copy constructor and assignment operator overloading that do the work for you. I need something like that in Rust.

推荐答案

您无法重载分配.将变量从一个位置移动到另一个位置是Rust所有权语义的核心组成部分，并且不可替代.

You cannot overload assignment. Moving a variable from one location to another is a core component of Rust's ownership semantics and is not overridable.

另一个答案建议您自定义实现Copy特性.这没有任何意义，因为 没有什么可实现的 :

Another answer suggests that you custom-implement the Copy trait. This makes no sense, as there's nothing to implement:

pub trait Copy: Clone { }

您可以为类型实现 Clone ，但是要使用clone，您必须明确地调用它:

You could implement Clone for a type, but to use clone you have to call it explicitly:

let foo = bar.clone();

实际分配仍然只是将位从右侧复制到左侧，唯一的区别是您不放弃对bar的所有权.

The actual assignment is still just copying bits from the right-hand side to the left-hand side, the only difference is that you don't give up ownership of bar.

如果您可以通过简单地复制位来复制您的类型，那么实施Copy是适当的. 如果可以通过执行某种功能来复制它，那么实现Clone是适当的.我没有办法在任何给定的类型赋值上隐式执行代码(我认为这是好事).

If your type can be duplicated by simply copying bits, then it's appropriate to implement Copy. If it can be duplicated by executing some kind of function, then it's appropriate to implement Clone. There is no way I know of to implicitly execute code at any given assignment of a type (and I count that as a good thing).

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