Implementing Traits

  1. trait Pet {
  2.     fn talk(&self) -> String;
  4.     fn greet(&self) {
  5.         println!("Oh you're a cutie! What's your name? {}", self.talk());
  6.     }
  7. }
  9. struct Dog {
  10.     name: String,
  11.     age: i8,
  12. }
  14. impl Pet for Dog {
  15.     fn talk(&self) -> String {
  16.         format!("Woof, my name is {}!", self.name)
  17.     }
  18. }
  20. fn main() {
  21.     let fido = Dog { name: String::from("Fido"), age: 5 };
  22.     fido.greet();
  23. }

  • To implement Trait for Type, you use an impl Trait for Type { .. } block.

  • Unlike Go interfaces, just having matching methods is not enough: a Cat type with a talk() method would not automatically satisfy Pet unless it is in an impl Pet block.

  • Traits may provide default implementations of some methods. Default implementations can rely on all the methods of the trait. In this case, greet is provided, and relies on talk.