stderr.log

Compiling study_lang v0.1.0 (file:///Users/axross/Dropbox/Workspace/study-rust/study_lang)
error[E0277]: the trait bound `Humanoid: Walkable` is not satisfied
  --> src/main.rs:68:3
   |
68 |   shift(humanoid);
   |   ^^^^^ the trait `Walkable` is not implemented for `Humanoid`
   |
   = note: required by `shift`

error: aborting due to previous error

error: Could not compile `study_lang`.

To learn more, run the command again with --verbose.

trait_bounds.rs

trait Walkable {
  fn walk(&self) -> ();
}

trait AlternativeWalkable {
  fn walk(&self) -> ();
}

struct Human {
  name: String,
}

struct Dog {
  breed: String,
}

struct Humanoid {
  id: i32,
}

impl Human {
  fn new(name: String) -> Human {
    Human { name: name }
  }
}

impl Dog {
  fn new(breed: String) -> Dog {
    Dog { breed: breed }
  }
}

impl Humanoid {
  fn new(id: i32) -> Humanoid {
    Humanoid { id: id }
  }
}

impl Walkable for Human {
  fn walk(&self) {
    println!("{} walks on the ground", self.name);
  }
}

impl Walkable for Dog {
  fn walk(&self) {
    println!("{} walks on the ground", self.breed);
  }
}

impl AlternativeWalkable for Humanoid {
  fn walk(&self) {
    println!("Humanoid(id:{}) emulates walking", self.id);
  }
}

fn shift<T: Walkable>(target: T) {
  target.walk();
}

fn main() {
  let human = Human::new("John".to_string());
  let dog = Dog::new("German Shepherd".to_string());
  let humanoid = Humanoid::new(31);

  shift(human);
  shift(dog);
  shift(humanoid);
}