module - 使用与结构同名的子模块的特征

Question

尝试编译以下 Rust 代码

mod traits {
    pub trait Dog {
        fn bark(&self) {
            println!("Bow");
        }
    }
}

struct Dog;

impl traits::Dog for Dog {}

fn main() {
    let dog = Dog;
    dog.bark();
}

给出错误信息

error[E0599]: no method named `bark` found for type `Dog` in the current scope
  --> src/main.rs:15:9
   |
9  | struct Dog;
   | ----------- method `bark` not found for this
...
15 |     dog.bark();
   |         ^^^^
   |
   = help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope, perhaps add a `use` for it:
   |
1  | use crate::traits::Dog;
   |

如果我添加 use crate::traits::Dog;，错误变为:

error[E0255]: the name `Dog` is defined multiple times
  --> src/main.rs:11:1
   |
1  | use crate::traits::Dog;
   |     ------------------ previous import of the trait `Dog` here
...
11 | struct Dog;
   | ^^^^^^^^^^^ `Dog` redefined here
   |
   = note: `Dog` must be defined only once in the type namespace of this module

如果我将 trait Dog 重命名为 trait DogTrait，一切正常。如何使用与主模块中的结构同名的子模块中的特征？

Answer 1

您可以在导入特征时重命名特征以获得相同的结果，而无需全局重命名特征:

use traits::Dog as DogTrait;

编译器现在甚至建议:

help: you can use `as` to change the binding name of the import
   |
1  | use crate::traits::Dog as OtherDog;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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