rust中dyn关键字的用法

以下代码是chatGPT给出的示例代码，智能AI果然NB

// Define a trait for an animal
trait Animal {
    fn make_sound(&self) -> &'static str;
}

// Define two structs that implement the Animal trait
struct Dog;
struct Cat;

impl Animal for Dog {
    fn make_sound(&self) -> &'static str {
        "Woof!"
    }
}

impl Animal for Cat {
    fn make_sound(&self) -> &'static str {
        "Meow!"
    }
}

// Define a function that returns a trait object on the heap
fn random_animal(random_number: f64) -> Box<dyn Animal> {
    if random_number < 0.5 {
        Box::new(Dog)
    } else {
        Box::new(Cat)
    }
}

fn main() {
    let random_number = 0.234;
    let animal = random_animal(random_number);
    println!("You got a {}!", animal.make_sound());
}
```