练习：健康统计

你正在实现一个健康监控系统。作为其中的一部分，你需要对用户的健康统计数据进行追踪。

You’ll start with a stubbed function in an impl block as well as a User struct definition. Your goal is to implement the stubbed out method on the User struct defined in the impl block.

Copy the code below to https://play.rust-lang.org/ and fill in the missing method:

  1. // TODO: remove this when you're done with your implementation.
  2. #![allow(unused_variables, dead_code)]
  4. #![allow(dead_code)]
  5. pub struct User {
  6.     name: String,
  7.     age: u32,
  8.     height: f32,
  9.     visit_count: usize,
  10.     last_blood_pressure: Option<(u32, u32)>,
  11. }
  13. pub struct Measurements {
  14.     height: f32,
  15.     blood_pressure: (u32, u32),
  16. }
  18. pub struct HealthReport<'a> {
  19.     patient_name: &'a str,
  20.     visit_count: u32,
  21.     height_change: f32,
  22.     blood_pressure_change: Option<(i32, i32)>,
  23. }
  25. impl User {
  26.     pub fn new(name: String, age: u32, height: f32) -> Self {
  27.         Self { name, age, height, visit_count: 0, last_blood_pressure: None }
  28.     }
  30.     pub fn visit_doctor(&mut self, measurements: Measurements) -> HealthReport {
  31.         todo!("Update a user's statistics based on measurements from a visit to the doctor")
  32.     }
  33. }
  35. fn main() {
  36.     let bob = User::new(String::from("Bob"), 32, 155.2);
  37.     println!("I'm {} and my age is {}", bob.name, bob.age);
  38. }
  40. #[test]
  41. fn test_visit() {
  42.     let mut bob = User::new(String::from("Bob"), 32, 155.2);
  43.     assert_eq!(bob.visit_count, 0);
  44.     let report =
  45.         bob.visit_doctor(Measurements { height: 156.1, blood_pressure: (120, 80) });
  46.     assert_eq!(report.patient_name, "Bob");
  47.     assert_eq!(report.visit_count, 1);
  48.     assert_eq!(report.blood_pressure_change, None);
  50.     let report =
  51.         bob.visit_doctor(Measurements { height: 156.1, blood_pressure: (115, 76) });
  53.     assert_eq!(report.visit_count, 2);
  54.     assert_eq!(report.blood_pressure_change, Some((-5, -4)));
  55. }