solution to exercise 04_05

Co-authored-by: Felix Pherry <182051.FELIX@klgroup.local>

Cargo.toml

@@ -1,3 +1,6 @@
 [workspace]
 members = ["exercises/*/*", "helpers/common", "helpers/mdbook-exercise-linker", "helpers/ticket_fields"]
 resolver = "2"
+
+[profile.dev]
+overflow-checks = false

book/src/04_traits/05_trait_bounds.md

@@ -58,7 +58,7 @@ We can do better using **generics**.\
 Generics allow us to write code that works with a **type parameter** instead of a concrete type:
 
 ```rust
-fn print_if_even<T>(n: T) 
+fn print_if_even<T>(n: T)
 where
     T: IsEven + Debug
 {
@@ -125,7 +125,7 @@ body is present.
 All the examples above used a **`where` clause** to specify trait bounds:
 
 ```rust
-fn print_if_even<T>(n: T) 
+fn print_if_even<T>(n: T)
 where
     T: IsEven + Debug
 //  ^^^^^^^^^^^^^^^^^
@@ -160,7 +160,7 @@ fn print_if_even<Number: IsEven + Debug>(n: Number) {
 It is actually **desirable** to use meaningful names when there are multiple type parameters at play or when the name
 `T` doesn't convey enough information about the type's role in the function.
 Maximize clarity and readability when naming type parameters, just as you would with variables or function parameters.
-Follow Rust's conventions though: use camel case for type parameter names.
+Follow Rust's conventions, though: use [upper camel case for type parameter names](https://rust-lang.github.io/api-guidelines/naming.html#casing-conforms-to-rfc-430-c-case).
 
 ## The function signature is king
 

book/src/05_ticket_v2/09_error_trait.md

@@ -7,7 +7,7 @@ pass it to the `panic!` macro.\
 This is a (rudimentary) example of **error reporting**: transforming an error type into a representation that can be
 shown to a user, a service operator, or a developer.
 
-It's not practical for each Rust developer to come up with their own error reporting strategy: it'd a waste of time
+It's not practical for each Rust developer to come up with their own error reporting strategy: it'd be a waste of time
 and it wouldn't compose well across projects.
 That's why Rust provides the `std::error::Error` trait.
 

exercises/01_intro/00_welcome/src/lib.rs

@@ -17,7 +17,7 @@
 // You can also find solutions to all exercises in the `solutions` git branch.
 fn greeting() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to learn Rust!"
 }
 
 // Your solutions will be automatically verified by a set of tests.

exercises/01_intro/01_syntax/src/lib.rs

@@ -3,7 +3,7 @@
 //  partner in this course and it'll often guide you in the right direction!
 //
 // The input parameters should have the same type of the return type.
-fn compute(a, b) -> u32 {
+fn compute(a: u32, b: u32) -> u32 {
     // Don't touch the function body.
     a + b * 2
 }
@@ -16,4 +16,4 @@ mod tests {
     fn case() {
         assert_eq!(compute(1, 2), 5);
     }
-}
+}

exercises/02_basic_calculator/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to build a calculator in Rust!"
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/01_integers/src/lib.rs

@@ -1,6 +1,6 @@
 fn compute(a: u32, b: u32) -> u32 {
     // TODO: change the line below to fix the compiler error and make the tests pass.
-    a + b * 4u8
+    a + b * 4u32
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/02_variables/src/lib.rs

@@ -8,7 +8,7 @@
 pub fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
     // TODO: define a variable named `distance` with the right value to get tests to pass
     //  Do you need to annotate the type of `distance`? Why or why not?
-
+    let distance: u32 = end - start;
     // Don't change the line below
     distance / time_elapsed
 }

exercises/02_basic_calculator/03_if_else/src/lib.rs

@@ -1,6 +1,6 @@
 /// Return `true` if `n` is even, `false` otherwise.
 fn is_even(n: u32) -> bool {
-    todo!()
+    n % 2 == 0
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/04_panics/src/lib.rs

@@ -2,7 +2,9 @@
 /// calculate the average speed of the journey.
 fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
     // TODO: Panic with a custom message if `time_elapsed` is 0
-
+    if time_elapsed == 0 {
+        panic!("The journey took no time at all, that's impossible!");
+    }
     (end - start) / time_elapsed
 }
 

exercises/02_basic_calculator/05_factorial/src/lib.rs

@@ -9,6 +9,13 @@
 // `factorial(2)` to return `2`, and so on.
 //
 // Use only what you learned! No loops yet, so you'll have to use recursion!
+fn factorial(n: u16) -> u16 {
+    if n == 0 {
+        1
+    } else {
+        n * factorial(n - 1)
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/02_basic_calculator/06_while/src/lib.rs

@@ -4,7 +4,13 @@ pub fn factorial(n: u32) -> u32 {
     // interprets as "I'll get back to this later", thus
     // suppressing type errors.
     // It panics at runtime.
-    todo!()
+    let mut result: u32 = 1; // base case
+    let mut i: u32 = 1;
+    while i <= n {
+        result *= i;
+        i += 1;
+    }
+    result
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/07_for/src/lib.rs

@@ -1,6 +1,10 @@
 // Rewrite the factorial function using a `for` loop.
 pub fn factorial(n: u32) -> u32 {
-    todo!()
+    let mut result: u32 = 1; // base case
+    for i in 2..=n {
+        result *= i;
+    }
+    result
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/09_saturating/src/lib.rs

@@ -1,9 +1,9 @@
 pub fn factorial(n: u32) -> u32 {
-    let mut result = 1;
+    let mut result: u32 = 1;
     for i in 1..=n {
         // Use saturating multiplication to stop at the maximum value of u32
         // rather than overflowing and wrapping around
-        result *= i;
+        result = result.saturating_mul(i);
     }
     result
 }

exercises/02_basic_calculator/10_as_casting/src/lib.rs

@@ -6,7 +6,7 @@ mod tests {
 
     #[test]
     fn u16_to_u32() {
-        let v: u32 = todo!();
+        let v: u32 = 47;
         assert_eq!(47u16 as u32, v);
     }
 
@@ -24,14 +24,14 @@ mod tests {
         // You could solve this by using exactly the same expression as above,
         // but that would defeat the purpose of the exercise. Instead, use a genuine
         // `i8` value that is equivalent to `255` when converted from `u8`.
-        let y: i8 = todo!();
+        let y: i8 = -1;
 
         assert_eq!(x, y);
     }
 
     #[test]
     fn bool_to_u8() {
-        let v: u8 = todo!();
+        let v: u8 = 1;
         assert_eq!(true as u8, v);
     }
 }

exercises/03_ticket_v1/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to start modelling a software ticket!"
 }
 
 #[cfg(test)]

exercises/03_ticket_v1/01_struct/src/lib.rs

@@ -4,6 +4,16 @@
 //
 // It should also have a method named `is_available` that returns a `true` if the quantity is
 // greater than 0, otherwise `false`.
+struct Order {
+    price: u8,
+    quantity: u8,
+}
+
+impl Order {
+    fn is_available(self) -> bool {
+        self.quantity > 0
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/03_ticket_v1/02_validation/src/lib.rs

@@ -17,7 +17,22 @@ impl Ticket {
     // as well as some `String` methods. Use the documentation of Rust's standard library
     // to find the most appropriate options -> https://doc.rust-lang.org/std/string/struct.String.html
     fn new(title: String, description: String, status: String) -> Self {
-        todo!();
+        if status != "To-Do" && status != "In Progress" && status != "Done" {
+            panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed")
+        }
+        if title.is_empty() {
+            panic!("Title cannot be empty")
+        }
+        if description.is_empty() {
+            panic!("Description cannot be empty")
+        }
+        if title.len() > 50 {
+            panic!("Title cannot be longer than 50 bytes")
+        }
+        if description.len() > 500 {
+            panic!("Description cannot be longer than 500 bytes")
+        }
+
         Self {
             title,
             description,

exercises/03_ticket_v1/03_modules/src/lib.rs

@@ -1,6 +1,7 @@
 mod helpers {
     // TODO: Make this code compile, either by adding a `use` statement or by using
     //  the appropriate path to refer to the `Ticket` struct.
+    use super::Ticket;
 
     fn create_todo_ticket(title: String, description: String) -> Ticket {
         Ticket::new(title, description, "To-Do".into())

exercises/03_ticket_v1/04_visibility/src/lib.rs

@@ -1,12 +1,12 @@
 mod ticket {
-    struct Ticket {
+    pub struct Ticket {
         title: String,
         description: String,
         status: String,
     }
 
     impl Ticket {
-        fn new(title: String, description: String, status: String) -> Ticket {
+        pub fn new(title: String, description: String, status: String) -> Ticket {
             if title.is_empty() {
                 panic!("Title cannot be empty");
             }
@@ -55,7 +55,7 @@ mod tests {
         //
         // TODO: Once you have verified that the below does not compile,
         //   comment the line out to move on to the next exercise!
-        assert_eq!(ticket.description, "A description");
+        // assert_eq!(ticket.description, "A description");
     }
 
     fn encapsulation_cannot_be_violated() {
@@ -68,10 +68,10 @@ mod tests {
         //
         // TODO: Once you have verified that the below does not compile,
         //   comment the lines out to move on to the next exercise!
-        let ticket = Ticket {
-            title: "A title".into(),
-            description: "A description".into(),
-            status: "To-Do".into(),
-        };
+        // let ticket = Ticket {
+        //    title: "A title".into(),
+        //    description: "A description".into(),
+        //    status: "To-Do".into(),
+        // };
     }
 }

exercises/03_ticket_v1/05_encapsulation/src/lib.rs

@@ -34,6 +34,17 @@ pub mod ticket {
         //  - `title` that returns the `title` field.
         //  - `description` that returns the `description` field.
         //  - `status` that returns the `status` field.
+        pub fn title(self) -> String {
+            self.title
+        }
+
+        pub fn description(self) -> String {
+            self.description
+        }
+
+        pub fn status(self) -> String {
+            self.status
+        }
     }
 }
 

exercises/03_ticket_v1/06_ownership/src/lib.rs

@@ -34,16 +34,16 @@ impl Ticket {
         }
     }
 
-    pub fn title(self) -> String {
-        self.title
+    pub fn title(&self) -> &String {
+        &self.title
     }
 
-    pub fn description(self) -> String {
-        self.description
+    pub fn description(&self) -> &String {
+        &self.description
     }
 
-    pub fn status(self) -> String {
-        self.status
+    pub fn status(&self) -> &String {
+        &self.status
     }
 }
 

exercises/03_ticket_v1/07_setters/src/lib.rs

@@ -11,21 +11,9 @@ pub struct Ticket {
 
 impl Ticket {
     pub fn new(title: String, description: String, status: String) -> Ticket {
-        if title.is_empty() {
-            panic!("Title cannot be empty");
-        }
-        if title.len() > 50 {
-            panic!("Title cannot be longer than 50 bytes");
-        }
-        if description.is_empty() {
-            panic!("Description cannot be empty");
-        }
-        if description.len() > 500 {
-            panic!("Description cannot be longer than 500 bytes");
-        }
-        if status != "To-Do" && status != "In Progress" && status != "Done" {
-            panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed");
-        }
+        validate_title(&title);
+        validate_description(&description);
+        validate_status(&status);
 
         Ticket {
             title,
@@ -45,6 +33,45 @@ impl Ticket {
     pub fn status(&self) -> &String {
         &self.status
     }
+
+    pub fn set_title(&mut self, title: String) {
+        validate_title(&title);
+        self.title = title;
+    }
+
+    pub fn set_description(&mut self, description: String) {
+        validate_description(&description);
+        self.description = description;
+    }
+
+    pub fn set_status(&mut self, status: String) {
+        validate_status(&status);
+        self.status = status;
+    }
+}
+
+fn validate_title(title: &String) {
+    if title.is_empty() {
+        panic!("Title cannot be empty");
+    }
+    if title.len() > 50 {
+        panic!("Title cannot be longer than 50 bytes");
+    }
+}
+
+fn validate_description(description: &String) {
+    if description.is_empty() {
+        panic!("Description cannot be empty");
+    }
+    if description.len() > 500 {
+        panic!("Description cannot be longer than 500 bytes");
+    }
+}
+
+fn validate_status(status: &String) {
+    if status != "To-Do" && status != "In Progress" && status != "Done" {
+        panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed");
+    }
 }
 
 #[cfg(test)]

exercises/03_ticket_v1/08_stack/src/lib.rs

@@ -6,16 +6,16 @@ mod tests {
 
     #[test]
     fn u16_size() {
-        assert_eq!(size_of::<u16>(), todo!());
+        assert_eq!(size_of::<u16>(), 2);
     }
 
     #[test]
     fn i32_size() {
-        assert_eq!(size_of::<i32>(), todo!());
+        assert_eq!(size_of::<i32>(), 4);
     }
 
     #[test]
     fn bool_size() {
-        assert_eq!(size_of::<bool>(), todo!());
+        assert_eq!(size_of::<bool>(), 1);
     }
 }

exercises/03_ticket_v1/09_heap/src/lib.rs

@@ -13,7 +13,7 @@ mod tests {
 
     #[test]
     fn string_size() {
-        assert_eq!(size_of::<String>(), todo!());
+        assert_eq!(size_of::<String>(), 24);
     }
 
     #[test]
@@ -23,6 +23,6 @@ mod tests {
         // but, in general, the memory layout of structs is a more complex topic.
         // If you're curious, check out the "Data layout" section of the Rustonomicon
         // https://doc.rust-lang.org/nomicon/data.html for more information.
-        assert_eq!(size_of::<Ticket>(), todo!());
+        assert_eq!(size_of::<Ticket>(), 72);
     }
 }

exercises/03_ticket_v1/10_references_in_memory/src/lib.rs

@@ -13,16 +13,16 @@ mod tests {
 
     #[test]
     fn u16_ref_size() {
-        assert_eq!(size_of::<&u16>(), todo!());
+        assert_eq!(size_of::<&u16>(), 8);
     }
 
     #[test]
     fn u64_mut_ref_size() {
-        assert_eq!(size_of::<&mut u64>(), todo!());
+        assert_eq!(size_of::<&mut u64>(), 8);
     }
 
     #[test]
     fn ticket_ref_size() {
-        assert_eq!(size_of::<&Ticket>(), todo!());
+        assert_eq!(size_of::<&Ticket>(), 8);
     }
 }

exercises/03_ticket_v1/11_destructor/src/lib.rs

@@ -2,7 +2,7 @@
 // We'll pick the concept up again in a later chapter after covering traits and
 // interior mutability.
 fn outro() -> &'static str {
-    "I have a basic understanding of __!"
+    "I have a basic understanding of destructors!"
 }
 
 #[cfg(test)]

exercises/03_ticket_v1/12_outro/src/lib.rs

@@ -11,3 +11,74 @@
 // Integration here has a very specific meaning: they test **the public API** of your project.
 // You'll need to pay attention to the visibility of your types and methods; integration
 // tests can't access private or `pub(crate)` items.
+pub struct Order {
+    product_name: String,
+    quantity: u32,
+    unit_price: u32,
+}
+
+impl Order {
+    pub fn new(product_name: String, quantity: u32, unit_price: u32) -> Order {
+        validate_product_name(&product_name);
+        validate_quantity(&quantity);
+        validate_unit_price(&unit_price);
+
+        Order {
+            product_name,
+            quantity,
+            unit_price,
+        }
+    }
+
+    pub fn product_name(&self) -> &String {
+        &self.product_name
+    }
+
+    pub fn quantity(&self) -> &u32 {
+        &self.quantity
+    }
+
+    pub fn unit_price(&self) -> &u32 {
+        &self.unit_price
+    }
+
+    pub fn set_product_name(&mut self, product_name: String) {
+        validate_product_name(&product_name);
+        self.product_name = product_name;
+    }
+
+    pub fn set_quantity(&mut self, quantity: u32) {
+        validate_quantity(&quantity);
+        self.quantity = quantity;
+    }
+
+    pub fn set_unit_price(&mut self, unit_price: u32) {
+        validate_unit_price(&unit_price);
+        self.unit_price = unit_price;
+    }
+
+    pub fn total(&self) -> u32 {
+        self.quantity * self.unit_price
+    }
+}
+
+fn validate_product_name(product_name: &String) {
+    if product_name.is_empty() {
+        panic!("Product name cannot be empty");
+    }
+    if product_name.len() > 300 {
+        panic!("Product name cannot be longer than 300 bytes");
+    }
+}
+
+fn validate_quantity(quantity: &u32) {
+    if quantity == &0 {
+        panic!("Quantity must be greater than zero");
+    }
+}
+
+fn validate_unit_price(unit_price: &u32) {
+    if unit_price == &0 {
+        panic!("Unit price must be greater than zero");
+    }
+}

exercises/04_traits/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to learn about traits!"
 }
 
 #[cfg(test)]

exercises/04_traits/01_trait/src/lib.rs

@@ -3,6 +3,22 @@
 //
 // Then implement the trait for `u32` and `i32`.
 
+pub trait IsEven {
+    fn is_even(self) -> bool;
+}
+
+impl IsEven for u32 {
+    fn is_even(self) -> bool {
+        self % 2 == 0
+    }
+}
+
+impl IsEven for i32 {
+    fn is_even(self) -> bool {
+        self % 2 == 0
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/04_traits/02_orphan_rule/src/lib.rs

@@ -3,9 +3,3 @@
 //  a foreign type (`u32`, from `std`).
 //  Look at the compiler error to get familiar with what it looks like.
 //  Then delete the code below and move on to the next exercise.
-
-impl PartialEq for u32 {
-    fn eq(&self, _other: &Self) -> bool {
-        todo!()
-    }
-}

exercises/04_traits/03_operator_overloading/src/lib.rs

@@ -8,7 +8,13 @@ struct Ticket {
 
 // TODO: Implement the `PartialEq` trait for `Ticket`.
 
-impl PartialEq for Ticket {}
+impl PartialEq for Ticket {
+    fn eq(&self, other: &Self) -> bool {
+        self.title == other.title
+            && self.description == other.description
+            && self.status == other.status
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/04_traits/04_derive/src/lib.rs

@@ -8,7 +8,7 @@
 // print both sides of the comparison to the terminal.
 // If the compared type doesn't implement `Debug`, it doesn't know how to represent them!
 
-#[derive(PartialEq)]
+#[derive(Debug, PartialEq)]
 struct Ticket {
     title: String,
     description: String,

exercises/04_traits/05_trait_bounds/src/lib.rs

@@ -6,7 +6,10 @@
 // collections (e.g. BTreeMap).
 
 /// Return the minimum of two values.
-pub fn min<T>(left: T, right: T) -> T {
+pub fn min<T>(left: T, right: T) -> T
+where
+    T: Ord,
+{
     if left <= right {
         left
     } else {