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// 让代码工作
use std::ops::Deref;

struct MyBox<T>(T);

impl<T> Deref for MyBox<T> {
    type Target = T;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

fn main() {
    let x = MyBox(5);
    assert_eq!(*x, 5);
    println!("Success!");
}

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// 让代码工作
use std::ops::Deref;

struct MyBox<T>(T);

impl<T> Deref for MyBox<T> {
    type Target = T;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

fn hello(name: &str) {
    println!("Hello, {}!", name);
}

fn main() {
    let m = MyBox(String::from("Rust"));
    hello(&m);
    println!("Success!");
}

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// 填空
use std::ops::{Deref, DerefMut};

struct MyBox<T>(T);

impl<T> Deref for MyBox<T> {
    type Target = T;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl<T> DerefMut for MyBox<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}

fn main() {
    let mut s = MyBox(String::from("hello"));
    s.__.push_str(", world");
    assert_eq!(*s, "hello, world");
    println!("Success!");
}