Rust进阶(6)-drop、trait清理代码

drop、trait清理代码

概述

Drop trait类似于其它语言中的析构函数，当值离开作用域的时候执行此函数的代码

基本使用

struct Dog {
    name: String,
}

impl Drop for Dog {
    fn drop(&mut self) {
        println!("Dog {} leave", self.name);
    }
}

fn main() {
    let a = Dog { name: String::from("wangcai") };
    {
        let b = Dog { name: String::from("dahuang") };
        println!("0 +++++++++++++")
    }
    println!("1 +++++++++++++")
}

输出结果：
表示作用域执行完，才开始释放

0 +++++++++++++
Dog dahuang leave
1 +++++++++++++
Dog wangcai leave

drop提前释放

不允许显式调用drop

struct Dog {
    name: String,
}

impl Drop for Dog {
    fn drop(&mut self) {
        println!("Dog {} leave", self.name);
    }
}

fn main() {
    let a = Dog { name: String::from("wangcai") };
    let b = Dog { name: String::from("dahuang") };
    //提前释放
    //b.drop();  //不允许显式调用`drop`,此操作会报错
    drop(b);  //正确释放
    drop(a);
    println!("0 +++++++++++++")
}

参考

[1] Rust 程序设计语言