trait Noisy { fn speak(&self); } struct Cat { meows : usize, how_hungry : isize, name : String, } impl Cat { pub fn eat(&self) -> bool { if self.how_hungry > 0 { println!("OM NOM NOM"); self.how_hungry -= 2; return true; } else { println!("Not hungry!"); return false; } } } impl Noisy for Cat { fn speak(&self) { self.meow(); } } impl Cat { fn meow(&self) { println!("Meow"); self.meows += 1; if self.meows % 5 == 0 { self.how_hungry += 1; } } } fn cat(in_x : usize, in_y : isize, in_name: String) -> Cat { Cat { meows: in_x, how_hungry: in_y, name: in_name } } fn main() { let nyan: Box = Box::new(cat(0, 2, "nyan".to_string())) as Box; nyan.eat(); //~ ERROR no method named `eat` found }