basic-tutorial 0.1.0

basic-tutorial
Documentation 
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use std::fmt::Debug;
use std::fmt::Display;

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

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

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

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

    fn summarize(&self) -> String {
        format!("{}, by {} ({})", self.headline, self.author, self.location)
    }
}

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)
    }
}


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

pub fn notify_full<T: Summary>(item: T) {
    notify(item);
}

#[allow(unused)]
pub fn notify_two(item: impl Summary + Display) {}

#[allow(unused)]
pub fn notify_where<T, U>(t: T, u: U)
    where T: Display + Clone,
          U: Clone + Debug
{}

// 返回值中使用 `impl Trait` 语法
fn returns_summarizable() -> impl Summary {
    Tweet {
        username: String::from("horse_ebooks"),
        content: String::from("of course, as you probably already know, people"),
        reply: false,
        retweet: false,
    }
}

fn main() {
    let tweet = Tweet {
        username: String::from("horse_books"),
        content: String::from("of course, as you probably already know, people"),
        reply: false,
        retweet: false,
    };
    println!("1 new tweet: {}", tweet.summarize());
    println!("1 new tweet: {}", returns_summarizable().summarize());
}