Tuple Structs

If the field names are unimportant, you can use a tuple struct:

1. struct Point(i32, i32);

3. fn main() {
4. let p = Point(17, 23);
5. println!("({}, {})", p.0, p.1);
6. }

This is often used for single-field wrappers (called newtypes):

1. struct PoundOfForce(f64);
2. struct Newtons(f64);

4. fn compute_thruster_force() -> PoundOfForce {
5. todo!("Ask a rocket scientist at NASA")
6. }

8. fn set_thruster_force(force: Newtons) {
9. // ...
10. }

12. fn main() {
13. let force = compute_thruster_force();
14. set_thruster_force(force);
15. }
  • Newtypes are a great way to encode additional information about the value in a primitive type, for example:
  • The number is measured in some units: Newtons in the example above.
  • The value passed some validation when it was created, so you no longer have to validate it again at every use: ’PhoneNumber(String)orOddNumber(u32)`.
  • Demonstrate how to add a f64 value to a Newtons type by accessing the single field in the newtype.
  • Rust generally doesn’t like inexplicit things, like automatic unwrapping or for instance using booleans as integers.
  • Operator overloading is discussed on Day 3 (generics).