Methods

Rust has methods, they are simply functions that are associated with a particular type. The first argument of a method is an instance of the type it is associated with:

1. struct Rectangle {
2. width: u32,
3. height: u32,
4. }

6. impl Rectangle {
7. fn area(&self) -> u32 {
8. self.width * self.height
9. }

11. fn inc_width(&mut self, delta: u32) {
12. self.width += delta;
13. }
14. }

16. fn main() {
17. let mut rect = Rectangle { width: 10, height: 5 };
18. println!("old area: {}", rect.area());
19. rect.inc_width(5);
20. println!("new area: {}", rect.area());
21. }

• We will look much more at methods in today’s exercise and in tomorrow’s class.