Trait是Rust实现多态和代码复用的核心机制。本文从基础到高级全面讲解。 ## 定义与实现Trait ```rust trait Summary { fn summarize_author(&self) -> String; fn summarize(&self) -> String { format!("(Read more from {}...)", self.summarize_author()) } } struct Article { title: String, author: String, content: String, } impl Summary for Article { fn summarize_author(&self) -> String { self.author.clone() } fn summarize(&self) -> String { format!("{}, by {}", self.title, self.author) } } ``` ## Trait作为参数 ```rust fn notify(item: &impl Summary) { println!("Breaking news! {}", item.summarize()); } fn notify(item: &T) { println!("Breaking news! {}", item.summarize()); } fn notify(item: &T) {} ``` ## Trait对象 ```rust fn returns_summarizable() -> Box { Box::new(Article { title: String::from("Rust Traits"), author: String::from("Alice"), content: String::from("Trait content"), }) } ``` ## 常用标准库Trait - Clone / Copy：值复制语义 - Debug：格式化输出 - Default：默认值 - From / Into：类型转换 - Iterator：迭代器 - Read / Write：IO操作 ## 关联类型 ```rust trait Container { type Item; fn get(&self) -> &Self::Item; } ``` Trait是Rust最强大的特性之一，掌握它是成为Rust高手的关键。