#![allow(unused)]

use std::rc::Rc;
use std::path::PathBuf;

trait HasNew {
  fn new() -> Self;
  fn x(&self) -> Self;
  fn y(&self) -> Vec<Rc<Self>> where Self : Sized;
}

pub trait TreeNode
{
    fn children(&self) -> Rc<Self>;
}

struct X {
    x : u16
}

impl X {
    fn new() -> Self {
        X { x : 8 }
    }
}

impl TreeNode for X {
    fn children(&self) -> Rc<Self> {
        Rc::new(X::new())
    }
}

impl HasNew for u16{
    fn new() -> u16 {
        return 16;
    }

    fn x(&self) -> u16 {
        2 + 2
    }

    fn y(&self) -> Vec<Rc<u16>> {
        vec![Rc::new(2)]
    }
}

fn returns_t<T: HasNew>() -> T {
   return T::new();
}

fn main() {
     let u: u16 = returns_t();

     let t : Rc<TreeNode> = X::new().children();

     println!("u={}", u);
}