在为引用和非引用类型实现一个特征时，我是否必须实现它两次? [英] Do I have to implement a trait twice when implementing it for both reference and non-reference types?

问题描述

我想为引用和非引用类型实现一个特征.我是否必须两次实现这些功能，或者这样做不习惯?

I want to implement a trait for both a for reference and non-reference type. Do I have to implement the functions twice, or this is not idiomatic to do so?

这是演示代码:

struct Bar {}

trait Foo {
    fn hi(&self);
}

impl<'a> Foo for &'a Bar {
    fn hi(&self) {
        print!("hi")
    }
}

impl Foo for Bar {
    fn hi(&self) {
        print!("hi")
    }
}

fn main() {
    let bar = Bar {};
    (&bar).hi();
    &bar.hi();
}

推荐答案

这是借用特征.

use std::borrow::Borrow;

struct Bar;

trait Foo {
    fn hi(&self);
}

impl<B: Borrow<Bar>> Foo for B {
    fn hi(&self) {
        print!("hi")
    }
}

fn main() {
    let bar = Bar;
    (&bar).hi();
    &bar.hi();
}

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