Quiz 3: add Grade trait, and related methods; add trait bound syntax …

…to ReportCard struct; group into modules;

exercises/quiz3.rs

@@ -16,24 +16,74 @@
 //
 // Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+/// 'grade' module contains the Grade trait, which converts a grade to a string
+mod grade {
+    /// Trait to convert a grade (f32 or &str) to a string
+    pub trait Grade {
+        /// Method to convert a grade to a string
+        fn grade(&self) -> String;
+    }
+
+    impl Grade for f32 {
+        /// Method to convert a numeric grade to an alphabetic grade
+        fn grade(&self) -> String {
+            if *self >= 4.5 {
+                "A+".to_string()
+            } else if *self >= 4.0 {
+                "A".to_string()
+            } else if *self >= 3.5 {
+                "B+".to_string()
+            } else if *self >= 3.0 {
+                "B".to_string()
+            } else if *self >= 2.5 {
+                "C+".to_string()
+            } else if *self >= 2.0 {
+                "C".to_string()
+            } else if *self >= 1.5 {
+                "D+".to_string()
+            } else if *self >= 1.0 {
+                "D".to_string()
+            } else {
+                "F-".to_string()
+            }
+        }
+    }
 
-pub struct ReportCard {
-    pub grade: f32,
-    pub student_name: String,
-    pub student_age: u8,
+    impl Grade for &str {
+        fn grade(&self) -> String {
+            self.to_string()
+        }
+    }
 }
 
-impl ReportCard {
-    pub fn print(&self) -> String {
-        format!("{} ({}) - achieved a grade of {}",
-            &self.student_name, &self.student_age, &self.grade)
+/// 'report_card' module contains the ReportCard struct, which prints the report card with the student's name, age, and grade
+mod report_card {
+    use super::grade::Grade;
+    use std::fmt::Display;
+
+    /// Change grade to a generic type T that implements the Grade trait
+    pub struct ReportCard<T: Grade> {
+        pub grade: T,
+        pub student_name: String,
+        pub student_age: u8,
+    }
+
+    // Add trait bound syntax to the impl block to allow the use of the Grade trait, and Display (for self.grade)
+    impl<T: Grade + Display> ReportCard<T> {
+        /// Print the report card, showing the student's name, age, and grade
+        pub fn print(&self) -> String {
+            format!(
+                "{} ({}) - achieved a grade of {}",
+                &self.student_name, &self.student_age, &self.grade
+            )
+        }
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use super::grade::Grade;
+    use super::report_card::ReportCard;
 
     #[test]
     fn generate_numeric_report_card() {
@@ -50,9 +100,8 @@ mod tests {
 
     #[test]
     fn generate_alphabetic_report_card() {
-        // TODO: Make sure to change the grade here after you finish the exercise.
         let report_card = ReportCard {
-            grade: 2.1,
+            grade: "A+",
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };