rust_drop_order.rs

trait Engine {
    fn eval(&self) -> String;
}

struct JSEngine {
    name: String,
}

impl JSEngine {
    fn new(name: String) -> Self {
        Self { name }
    }
}
impl Engine for JSEngine {
    fn eval(&self) -> String {
        "js eval".to_string()
    }
}

impl Drop for JSEngine {
    fn drop(&mut self) {
        println!("drop JSEngine {}", self.nam);
    }
}
fn main() {

    let x = "js eval".to_string();
    if x == JSEngine::new("abc".into()).eval() {
        println!("inside {:?}", "if");
    }

    println!("------------- {:?}", "sep");

    match JSEngine::new("abc".into()).eval() {
        x => {
            println!("inside {:?}", "match");
        }
        _ => {
            println!("not match {:?}", "here");
        }
    }
    println!("------------- {:?}", "sep");

    let s = JSEngine::new("last".into()).eval();
    println!("s {:?}", s);
}