rust相同方法名调用顺序

1.优先匹配非trait实现，根据调用方式优先匹配

(&var).call()优先匹配&self实现

(&mut var).call()优先匹配&mut self实现

(var).call()优先匹配self实现

测试代码：

struct Nemo;

trait Say {
    fn say(&self);
}

trait SayMut {
    fn say(&mut self);
}

trait Sayonce {
    fn say(self);
}

impl Say for Nemo {
    fn say(&self) {
        println!("say bbb")
    }
}

impl SayMut for Nemo {
    fn say(&mut self) {
        println!("say ccc")
    }
}

impl Sayonce for Nemo {
    fn say(self) {
        println!("say ddd")
    }
}

impl Nemo {
    fn say(&self) {
        println!("say aaa")
    }
    // fn say(&mut self) {
    //     println!("say aaa")
    // }
    // fn say(&mut self) {
    //     println!("say aaa")
    // }
}

fn main() {
    let mut k = Nemo;
    (&k).say();
}

2.匹配trait实现，如果存在trait冲突，则报错

impl Say for Nemo {
    fn say(&self) {
        println!("say bbb")
    }
}

impl Sayonce for &Nemo {
    fn say(self) {
        println!("say ddd")
    }
}

fn main() {
    let mut k = Nemo;
    (&k).say();//multiple `say` found
}

3.Defer/DeferMut匹配，调用后重新匹配规则1、2。

4.转换匹配

self->&mut self

&mut self->& self

如果规则4匹配失败，执行规则3后再次执行规则4。

trait Say {
    fn say(&self);
}

trait SayMut {
    fn say(&mut self);
}

struct Nemo;

impl Nemo {}


impl Say for &mut &mut Nemo {
    fn say(&self) {
        println!("say bbb")
    }
}

impl SayMut for &mut Nemo {
    fn say(&mut self) {
        println!("say ccc")
    }
}

fn main() {
    let mut k: Nemo = Nemo;
    (&mut &mut &mut k).say();
}