finish generics exercises

exercises/generics/generics1.rs

@@ -1,10 +1,7 @@
 // This shopping list program isn't compiling!
 // Use your knowledge of generics to fix it.
 
-// I AM NOT DONE
-
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&str> = Vec::new();
     shopping_list.push("milk");
 }
-

exercises/generics/generics2.rs

@@ -1,13 +1,12 @@
 // This powerful wrapper provides the ability to store a positive integer value.
 // Rewrite it using generics so that it supports wrapping ANY type.
 
-// I AM NOT DONE
-struct Wrapper {
-    value: u32
+struct Wrapper<T> {
+    value: T,
 }
 
-impl Wrapper {
-    pub fn new(value: u32) -> Self {
+impl<T> Wrapper<T> {
+    pub fn new(value: T) -> Self {
         Wrapper { value }
     }
 }
@@ -18,7 +17,7 @@ mod tests {
 
     #[test]
     fn store_u32_in_wrapper() {
-        assert_eq!(Wrapper::new(42).value,  42);
+        assert_eq!(Wrapper::new(42).value, 42);
     }
 
     #[test]

exercises/generics/generics3.rs

@@ -6,18 +6,20 @@
 
 // Make the necessary code changes to support alphabetical report cards, thereby making
 // the second test pass.
+use std::fmt::{Debug, Display};
 
-// I AM NOT DONE
-pub struct ReportCard {
-    pub grade: f32,
+pub struct ReportCard<T> {
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T: Display + Debug> ReportCard<T> {
     pub fn print(&self) -> String {
-        format!("{} ({}) - achieved a grade of {}", 
-            &self.student_name, &self.student_age, &self.grade)
+        format!(
+            "{} ({}) - achieved a grade of {}",
+            &self.student_name, &self.student_age, &self.grade
+        )
     }
 }
 
@@ -32,17 +34,23 @@ mod tests {
             student_name: "Tom Wriggle".to_string(),
             student_age: 12,
         };
-        assert_eq!(report_card.print(), "Tom Wriggle (12) - achieved a grade of 2.1");
+        assert_eq!(
+            report_card.print(),
+            "Tom Wriggle (12) - achieved a grade of 2.1"
+        );
     }
 
     #[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+".to_string(),
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };
-        assert_eq!(report_card.print(), "Gary Plotter (11) - achieved a grade of A+");
+        assert_eq!(
+            report_card.print(),
+            "Gary Plotter (11) - achieved a grade of A+"
+        );
     }
 }