rust 神奇的特质

pub trait Summary {
    fn summarize_author(&self) -> String;

    fn summarize(&self) -> String {
        format!("(Default Read more from {}...)", self.summarize_author())
    }
}

pub struct NewsArticle {
    pub headline: String,
    pub location: String,
    pub author: String,
    pub content: String,
}

pub struct Tweet {
    pub username: String,
    pub content: String,
    pub reply: bool,
    pub retweet: bool,
}

impl Summary for Tweet {
    fn summarize_author(&self) -> String {
        format!("@{}", self.username)
    }
}

impl Summary for NewsArticle {
    fn summarize_author(&self) -> String {
        format!("@{}", self.author)
    }
    
    fn summarize(&self) -> String {
        format!("(NewsArticle Read more from {}...)", self.summarize_author())
    }
}

impl Summary for String {
    fn summarize_author(&self) -> String {
        format!("@{}", &self)
    }
    
    fn summarize(&self) -> String {
        format!("(Read more from {}...)", self.summarize_author())
    }
}

impl Summary for i64 {
    fn summarize_author(&self) -> String {
        format!("@{}", &self)
    }
    
    fn summarize(&self) -> String {
        format!("(Read more from {}...)", self.summarize_author())
    }
}

pub fn notify(item: impl Summary) {
    println!("Breaking news! {}", item.summarize());
}

fn main(){
    let article = NewsArticle {
        headline: String::from("Penguins win the Stanley Cup Championship!"),
        location: String::from("Pittsburgh, PA, USA"),
        author: String::from("Iceburgh"),
        content: String::from("The Pittsburgh Penguins once again are the best
        hockey team in the NHL."),
    };
    
    println!("New article available! {}", article.summarize());
    notify(article);

    let tweet = Tweet {
        username: String::from("horse_ebooks"),
        content: String::from("of course, as you probably already know, people"),
        reply: false,
        retweet: false,
    };
    
    println!("1 new tweet: {}", tweet.summarize());
    notify(tweet);
    notify(1000);
    notify(String::from("你好，特质，你很强"));

}

　　

使用trait，语言表达很强啊。  越来越喜欢它了。  

总结： 任何类型都可以实现特质。 类似于接口。