Lifetime Patterns

Patterns สำหรับ lifetime management

Basic Lifetime Annotation

// Function with lifetime
fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
    if x.len() > y.len() { x } else { y }
}

// Multiple lifetimes
fn first_word<'a, 'b>(s: &'a str, _other: &'b str) -> &'a str {
    s.split_whitespace().next().unwrap_or("")
}

fn main() {
    let s1 = String::from("hello");
    let s2 = String::from("world!");

    let result = longest(&s1, &s2);
    println!("Longest: {}", result);

    // Lifetime scopes
    let outer = String::from("outer");
    {
        let inner = String::from("inner string");
        let result = longest(&outer, &inner);
        println!("Result: {}", result);  // OK: both strings valid
    }
    // inner dropped here
    println!("Outer still valid: {}", outer);
}