特征名称之后的特征是什么意思？

发布于 2025-02-03 10:59:54 字数 213 浏览 2 评论 0 原文

我在阅读有关Rust的特征定义时遇到了这个特征的定义：

trait Enchanter: std::fmt::Debug {
    ...
}

由此我了解该特征的名称是 nchanter ，但我不明白 std ::格式：debug std ::格式>部分意味着它也是一个特征（我认为）。

原文

I came across this trait definition while reading about Rust:

trait Enchanter: std::fmt::Debug {
    ...
}

From this I understand that the name of the trait is Enchanter, but I do not understand what the std::Format:Debug part implies since it is also a trait (I think).

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时光暖心i 2025-02-10 10:59:55

这是在宣布a supertrait 。它等同于：

trait Enchanter
where
    Self: std::fmt::Debug,
{
}

简而言之，它需要任何想要实现 enchanter 的类型也可以实现 std :: fmt :: debug 。否则，：：

error[E0277]: `S` doesn't implement `Debug`
 --> src/lib.rs:4:6
  |
4 | impl Enchanter for S {}
  |      ^^^^^^^^^ `S` cannot be formatted using `{:?}`
  |
  = help: the trait `Debug` is not implemented for `S`
  = note: add `#[derive(Debug)]` to `S` or manually `impl Debug for S`
note: required by a bound in `Enchanter`
 --> src/lib.rs:1:18
  |
1 | trait Enchanter: std::fmt::Debug {}
  |                  ^^^^^^^^^^^^^^^ required by this bound in `Enchanter`

This is declaring a supertrait. It is equivalent to:

trait Enchanter
where
    Self: std::fmt::Debug,
{
}

In short, it requires any type that wants to implement Enchanter to also implement std::fmt::Debug. Otherwise, an error will be raised:

error[E0277]: `S` doesn't implement `Debug`
 --> src/lib.rs:4:6
  |
4 | impl Enchanter for S {}
  |      ^^^^^^^^^ `S` cannot be formatted using `{:?}`
  |
  = help: the trait `Debug` is not implemented for `S`
  = note: add `#[derive(Debug)]` to `S` or manually `impl Debug for S`
note: required by a bound in `Enchanter`
 --> src/lib.rs:1:18
  |
1 | trait Enchanter: std::fmt::Debug {}
  |                  ^^^^^^^^^^^^^^^ required by this bound in `Enchanter`

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