从结构中获取枚举字段:无法移出借用的内容

问题描述

我是 Rust 的新手，并试图围绕所有权/借用概念进行思考.现在我已将我的代码简化为这个会出现编译错误的最小代码示例.

pub struct Display {颜色:颜色，}酒吧枚举颜色{蓝色 = 0x1，红色 = 0x4，}impl 显示 {fn get_color_value(&self) ->u16{self.color 为 u16}}

src/display.rs:12:9: 12:13 错误:无法移出借来的内容src/display.rs:12 self.color 作为 u16^~~~错误:由于先前的错误而中止无法编译.

我仍然处于一切都是按价值复制的心态，在这种情况下，执行 self.color 是完全合法的，因为这会给我一份 颜色.显然，我错了.我在 SO 上发现了一些关于相同错误的其他问题，但没有解决我的问题.

据我所知，该字段由拥有 Display 的任何人拥有.因为我只借了一个对 Display 的引用，我不拥有它.提取 color 尝试转移所有权Color 对我来说是不可能的，因为我不拥有 Display.这是正确的吗?

我该如何解决?

解决方案

任何可以在 rust 中复制的东西都必须明确地带有 Copy 特性.Copy 过去是隐式的，但已更改(rfc).

据我所知，该领域归拥有显示器的任何人所有.由于我只是借用了对 Display 的引用，因此我不拥有它.提取颜色尝试将颜色的所有权转让给我，这是不可能的，因为我不拥有显示器.这是正确的吗?

是的.当您遇到此错误时，有三种可能的解决方案:

• 为类型派生特征Copy(如果适用)
• 使用/派生Clone (self.color.clone())
• 返回参考

为了解决这个问题，你为 Color 派生了 Copy:

#[derive(Copy, Clone)]酒吧枚举颜色{蓝色 = 0x1，红色 = 0x4，}

这与:

impl Copy for Color {}

I'm new to Rust and trying to wrap my head around the ownership/borrowing concept. Now I have reduced my code to this minimal code sample that gives a compile error.

pub struct Display {
    color: Color,
}

pub enum Color {
    Blue         = 0x1,
    Red          = 0x4,
}

impl Display {
    fn get_color_value(&self) -> u16 {
        self.color as u16
    }
}

I'm still in the everything is copied by value mindset, where it is perfectly legal to do self.color as that would get me a copy of Color. Apparently, I am wrong. I found some other questions about this same error on SO, but no solution to my issue.

As I understand it, the field is owned by whomever owns the Display. Since I only borrowed areference to the Display, I don't own it. Extracting color attempts to transfer ownership ofthe Color to me, which is not possible since I don't own the Display. Is this correct?

How do I solve it?

解决方案

Anything that can be copied in rust must be explicitly mared with a trait Copy. Copy was implicit in the past but that was changed (rfc).

Yes. When you encounter this error there are three possible solutions:

• Derive the trait Copy for the type (if appropriate)
• Use/derive Clone (self.color.clone())
• Return a reference

To solve this you derive Copy for Color:

#[derive(Copy, Clone)]
pub enum Color {
    Blue         = 0x1,
    Red          = 0x4,
}

This is the same as:

impl Copy for Color {}

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