Generic Methods

You can declare a generic type on your impl block:

  1. #[derive(Debug)]
  2. struct Point<T>(T, T);
  4. impl<T> Point<T> {
  5.     fn x(&self) -> &T {
  6.         &self.0  // + 10
  7.     }
  9.     // fn set_x(&mut self, x: T)
  10. }
  12. fn main() {
  13.     let p = Point(5, 10);
  14.     println!("p.x = {}", p.x());
  15. }
  • Q: Why T is specified twice in impl<T> Point<T> {}? Isn’t that redundant?
    • This is because it is a generic implementation section for generic type. They are independently generic.
    • It means these methods are defined for any T.
    • It is possible to write impl Point<u32> { .. }.
      • Point is still generic and you can use Point<f64>, but methods in this block will only be available for Point<u32>.