Solutions 2

exercises/error_handling/errors1.rs

@@ -5,14 +5,12 @@
 // construct to `Option` that can be used to express error conditions. Let's use it!
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
-pub fn generate_nametag_text(name: String) -> Option<String> {
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
     if name.is_empty() {
         // Empty names aren't allowed.
-        None
+        Err("`name` was empty; it must be nonempty.".into())
     } else {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     }
 }
 

exercises/error_handling/errors2.rs

@@ -17,14 +17,12 @@
 // one is a lot shorter!
 // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
+    let qty = item_quantity.parse::<i32>()?;
 
     Ok(qty * cost_per_item + processing_fee)
 }

exercises/error_handling/errors3.rs

@@ -4,11 +4,9 @@
 // Why not? What should we do to fix it?
 // Execute `rustlings hint errors3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
-fn main() {
+fn main() -> Result<(), ParseIntError> {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
@@ -20,6 +18,8 @@ fn main() {
         tokens -= cost;
         println!("You now have {} tokens.", tokens);
     }
+
+    return Ok(())
 }
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {

exercises/error_handling/errors4.rs

@@ -1,8 +1,6 @@
 // errors4.rs
 // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
 
@@ -15,7 +13,13 @@ enum CreationError {
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
         // Hmm...? Why is this only returning an Ok value?
-        Ok(PositiveNonzeroInteger(value as u64))
+        if value > 0 {
+            Ok(PositiveNonzeroInteger(value as u64))
+        } else if value == 0 {
+            Err(CreationError::Zero)
+        } else {
+            Err(CreationError::Negative)
+        }
     }
 }
 

exercises/error_handling/errors5.rs

@@ -7,7 +7,7 @@
 // For now, think of the `Box<dyn ...>` type as an "I want anything that does ???" type, which, given
 // Rust's usual standards for runtime safety, should strike you as somewhat lenient!
 
-// In short, this particular use case for boxes is for when you want to own a value and you care only that it is a 
+// In short, this particular use case for boxes is for when you want to own a value and you care only that it is a
 // type which implements a particular trait. To do so, The Box is declared as of type Box<dyn Trait> where Trait is the trait
 // the compiler looks for on any value used in that context. For this exercise, that context is the potential errors
 // which can be returned in a Result.
@@ -16,14 +16,12 @@
 
 // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::error;
 use std::fmt;
 use std::num::ParseIntError;
 
 // TODO: update the return type of `main()` to make this compile.
-fn main() -> Result<(), Box<dyn ???>> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);

exercises/error_handling/errors6.rs

@@ -8,8 +8,6 @@
 
 // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 // This is a custom error type that we will be using in `parse_pos_nonzero()`.
@@ -23,16 +21,16 @@ impl ParsePosNonzeroError {
     fn from_creation(err: CreationError) -> ParsePosNonzeroError {
         ParsePosNonzeroError::Creation(err)
     }
-    // TODO: add another error conversion function here.
-    // fn from_parseint...
+
+    fn from_parseint(err: ParseIntError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::ParseInt(err)
+    }
 }
 
 fn parse_pos_nonzero(s: &str)
     -> Result<PositiveNonzeroInteger, ParsePosNonzeroError>
 {
-    // TODO: change this to return an appropriate error instead of panicking
-    // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
+    let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parseint)?;
     PositiveNonzeroInteger::new(x)
         .map_err(ParsePosNonzeroError::from_creation)
 }

exercises/generics/generics1.rs

@@ -3,9 +3,7 @@
 
 // Execute `rustlings hint generics1` or use the `hint` watch subcommand for a hint.
 
-// 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

@@ -3,14 +3,12 @@
 
 // Execute `rustlings hint generics2` or use the `hint` watch subcommand for a hint.
 
-// 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 }
     }
 }

exercises/options/options1.rs

@@ -1,8 +1,6 @@
 // options1.rs
 // Execute `rustlings hint options1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 // This function returns how much icecream there is left in the fridge.
 // If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them
 // all, so there'll be no more left :(
@@ -10,7 +8,13 @@
 fn maybe_icecream(time_of_day: u16) -> Option<u16> {
     // We use the 24-hour system here, so 10PM is a value of 22
     // The Option output should gracefully handle cases where time_of_day > 24.
-    ???
+    if time_of_day < 22 {
+        Some(5)
+    } else if time_of_day <= 24 {
+        Some(0)
+    } else {
+        None
+    }
 }
 
 #[cfg(test)]
@@ -29,7 +33,7 @@ mod tests {
     #[test]
     fn raw_value() {
         // TODO: Fix this test. How do you get at the value contained in the Option?
-        let icecreams = maybe_icecream(12);
+        let icecreams = maybe_icecream(12).unwrap();
         assert_eq!(icecreams, 5);
     }
 }

exercises/options/options2.rs

@@ -1,8 +1,6 @@
 // options2.rs
 // Execute `rustlings hint options2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -13,7 +11,7 @@ mod tests {
         let optional_target = Some(target);
 
         // TODO: Make this an if let statement whose value is "Some" type
-        word = optional_target {
+        if let Some(word) = optional_target {
             assert_eq!(word, target);
         }
     }
@@ -28,7 +26,7 @@ mod tests {
 
         // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
         // You can stack `Option<T>`'s into while let and if let
-        integer = optional_integers.pop() {
+        while let Some(Some(integer)) = optional_integers.pop() {
             assert_eq!(integer, range);
             range -= 1;
         }

exercises/options/options3.rs

@@ -1,8 +1,6 @@
 // options3.rs
 // Execute `rustlings hint options3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 struct Point {
     x: i32,
     y: i32,
@@ -12,7 +10,7 @@ fn main() {
     let y: Option<Point> = Some(Point { x: 100, y: 200 });
 
     match y {
-        Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
+        Some(ref p) => println!("Co-ordinates are {},{} ", p.x, p.y),
         _ => println!("no match"),
     }
     y; // Fix without deleting this line.

exercises/quiz3.rs

@@ -14,15 +14,13 @@
 
 // Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
 
-// 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: std::fmt::Display> ReportCard<T> {
     pub fn print(&self) -> String {
         format!("{} ({}) - achieved a grade of {}",
             &self.student_name, &self.student_age, &self.grade)
@@ -50,7 +48,7 @@ mod tests {
     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,
         };

exercises/traits/traits1.rs

@@ -9,14 +9,14 @@
 // implementing this trait.
 // Execute `rustlings hint traits1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
 impl AppendBar for String {
-    //Add your code here
+    fn append_bar(self) -> Self {
+        self + "Bar"
+    }
 }
 
 fn main() {

exercises/traits/traits2.rs

@@ -11,13 +11,16 @@
 // you can do this!
 // Execute `rustlings hint traits2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
-//TODO: Add your code here
+impl AppendBar for Vec<String> {
+    fn append_bar(mut self) -> Self {
+        self.push("Bar".to_string());
+        self
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/traits/traits3.rs

@@ -7,10 +7,10 @@
 // Consider what you can add to the Licensed trait.
 // Execute `rustlings hint traits3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub trait Licensed {
-    fn licensing_info(&self) -> String;
+    fn licensing_info(&self) -> String {
+        "Some information".to_string()
+    }
 }
 
 struct SomeSoftware {

exercises/traits/traits4.rs

@@ -4,8 +4,6 @@
 // Don't change any line other than the marked one.
 // Execute `rustlings hint traits4` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub trait Licensed {
     fn licensing_info(&self) -> String {
         "some information".to_string()
@@ -20,7 +18,7 @@ impl Licensed for SomeSoftware {}
 impl Licensed for OtherSoftware {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn compare_license_types(software: ??, software_two: ??) -> bool {
+fn compare_license_types(software: impl Licensed, software_two: impl Licensed) -> bool {
     software.licensing_info() == software_two.licensing_info()
 }
 

exercises/traits/traits5.rs

@@ -4,8 +4,6 @@
 // Don't change any line other than the marked one.
 // Execute `rustlings hint traits5` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub trait SomeTrait {
     fn some_function(&self) -> bool {
         true
@@ -27,7 +25,7 @@ impl SomeTrait for OtherStruct {}
 impl OtherTrait for OtherStruct {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn some_func(item: ??) -> bool {
+fn some_func(item: impl SomeTrait + OtherTrait) -> bool {
     item.some_function() && item.other_function()
 }