Traits

Ek trait un methods ka set define karta hai jo ek type implement kar sakta hai — doosri languages mein interface jaisa. Ek martaba jab koi type ek trait implement kar deta hai, aap us trait ke methods ko directly usper call kar sakte hain.

main.rs

Khud try karo →

trait Greet {
    fn greet(&self) -> String;
}

struct Person {
    name: String,
}

impl Greet for Person {
    fn greet(&self) -> String {
        format!("Hello, my name is {}", self.name)
    }
}

fn main() {
    let alice = Person { name: String::from("Alice") };
    println!("{}", alice.greet());
}

Output

Hello, my name is Alice

Trait bounds

Ek generic function require kar sakta hai ke uska type parameter ek particular trait implement kare, jo T: Greet se likha jaata hai. Yeh greet_everyone ko kisi bhi aise type ka slice accept karne deta hai jo Greet implement karta ho, sirf khaas tor par Person nahi — function ek martaba likha jaata hai aur har us type ke liye kaam karta hai jo bound ko satisfy karta hai.

main.rs

Khud try karo →

trait Greet {
    fn greet(&self) -> String;
}

struct Person {
    name: String,
}

impl Greet for Person {
    fn greet(&self) -> String {
        format!("Hello, my name is {}", self.name)
    }
}

fn greet_everyone<T: Greet>(items: &[T]) {
    for item in items {
        println!("{}", item.greet());
    }
}

fn main() {
    let people = vec![
        Person { name: String::from("Alice") },
        Person { name: String::from("Bob") },
    ];
    greet_everyone(&people);
}

Output

Hello, my name is Alice
Hello, my name is Bob

Aage: generics — ek aisa function ya struct likhna jo kai types ke across kaam kare, woh general mechanism jispar trait bounds bante hain.

Practice Exercise

Ek trait Area define karein jiska method area(&self) -> f64 ho. Ise ek struct Square { side: f64 } ke liye implement karein taake area(), side * side wapas kare. side 4.0 wala ek Square banayein aur uska area() print karein.

← Iterators aur Closures Generics →