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Restriction by trait Grade so that the ReportCard has and ONLY has two types: numeric and alphabetic.

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This commit is contained in:
1vk3y 2024-10-07 13:17:40 +08:00
parent e852e60416
commit 1444cb9737
1 changed files with 17 additions and 5 deletions
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22
solutions/quizzes/quiz3.rs
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@ -9,9 +9,21 @@
use std::fmt::Display; use std::fmt::Display;
// Make the struct generic over `T`. // Grade Trait
struct ReportCard<T> { trait Grade {}
// ^^^ //^^^^^^^^^^^^
// Implements the trait for `f32` (numeric, e.g. 1.0 -> 5.5)
impl Grade for f32 {}
//^^^^^^^^^^^^^^^^^^^
// Implements the trait for `str` (alphabetic, A+ -> F-)
impl Grade for &str {}
//^^^^^^^^^^^^^^^^^^^^
// Make the struct generic over `T: Grade`.
struct ReportCard<T: Grade> {
// ^^^^^^^^^^
grade: T, grade: T,
// ^ // ^
student_name: String, student_name: String,
@ -19,8 +31,8 @@ struct ReportCard<T> {
} }
// To be able to print the grade, it has to implement the `Display` trait. // To be able to print the grade, it has to implement the `Display` trait.
impl<T: Display> ReportCard<T> { impl<T: Display + Grade> ReportCard<T> {
// ^^^^^^^ require that `T` implements `Display`. // ^^^^^^^^^^^^^^^ require that `T` implements `Display` and `Grade`.
fn print(&self) -> String { fn print(&self) -> String {
format!( format!(
"{} ({}) - achieved a grade of {}", "{} ({}) - achieved a grade of {}",