pub trait UserCommunication {
    async fn send_sms(self: &Self, phone: &str, code: &str);
    async fn send_email(self: &Self, email: &str, code: &str);
}

pub struct AuthenticationService {
    communicator: Box<dyn UserCommunication>,
}

如上代码，希望communicator是个动态分发的trait，不咋想用async-trait实现