feat: trait exercise

src/main.rs

@@ -5,6 +5,7 @@ mod float;
 mod signed;
 mod string;
 mod todo;
+mod traits;
 mod unsigned;
 mod user_struct;
 

src/traits/drop_trait.rs

@@ -0,0 +1,23 @@
+// // TODO: implement a so-called "Drop bomb": a type that panics when dropped
+// //  unless a certain operation has been performed on it.
+// //  You can see the expected API in the tests below.
+
+// #[cfg(test)]
+// mod tests {
+//     use super::*;
+
+//     #[test]
+//     #[should_panic]
+//     fn test_drop_bomb() {
+//         let bomb = DropBomb::new();
+//         // The bomb should panic when dropped
+//     }
+
+//     #[test]
+//     fn test_defused_drop_bomb() {
+//         let mut bomb = DropBomb::new();
+//         bomb.defuse();
+//         // The bomb should not panic when dropped
+//         // since it has been defused
+//     }
+// }

src/traits/eight_size_trait.rs

@@ -0,0 +1,7 @@
+pub fn example() {
+    // Trying to get the size of a str (or any other DST)
+    // via `std::mem::size_of` will result in a compile-time error.
+    //
+    // TODO: Comment out the following line and move on to the next exercise.
+    std::mem::size_of::<&str>();
+}

src/traits/eleven_clone_trait.rs

@@ -0,0 +1,28 @@
+// TODO: add the necessary `Clone` implementations (and invocations)
+//  to get the code to compile.
+
+pub fn summary(ticket: Ticket) -> (Ticket, Summary) {
+    let m = ticket.clone().summary();
+    (ticket, m)
+}
+
+#[derive(Clone)]
+pub struct Ticket {
+    pub title: String,
+    pub description: String,
+    pub status: String,
+}
+
+impl Ticket {
+    pub fn summary(self) -> Summary {
+        Summary {
+            title: self.title,
+            status: self.status,
+        }
+    }
+}
+
+pub struct Summary {
+    pub title: String,
+    pub status: String,
+}

src/traits/five_trait_bound.rs

@@ -0,0 +1,15 @@
+// TODO: Add the necessary trait bounds to `min` so that it compiles successfully.
+//   Refer to the documentation of the `std::cmp` module for more information on the traits you might need.
+//
+// Note: there are different trait bounds that'll make the compiler happy, but they come with
+// different _semantics_. We'll cover those differences later in the course when we talk about ordered
+// collections (e.g. BTreeMap).
+
+/// Return the minimum of two values.
+pub fn min<T: PartialOrd>(left: T, right: T) -> T {
+    if left <= right {
+        left
+    } else {
+        right
+    }
+}

src/traits/four_derive_trait.rs

@@ -0,0 +1,90 @@
+// TODO: A (derivable) trait implementation is missing for this exercise to compile successfully.
+//   Fix it!
+//
+// # `Debug` primer
+//
+// `Debug` returns a representation of a Rust type that's suitable for debugging (hence the name).
+// `assert_eq!` requires `Ticket` to implement `Debug` because, when the assertion fails, it tries to
+// 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, Debug)]
+struct Ticket {
+    title: String,
+    description: String,
+    status: String,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_partial_eq() {
+        let title = "title";
+        let description = "description";
+        let status = "To-Do";
+        let ticket1 = Ticket {
+            title: title.to_string(),
+            description: description.to_string(),
+            status: status.to_string(),
+        };
+        let ticket2 = Ticket {
+            title: title.to_string(),
+            description: description.to_string(),
+            status: status.to_string(),
+        };
+        assert_eq!(ticket1, ticket2);
+    }
+
+    #[test]
+    fn test_description_not_matching() {
+        let title = "title";
+        let status = "To-Do";
+        let ticket1 = Ticket {
+            title: title.to_string(),
+            description: "description".to_string(),
+            status: status.to_string(),
+        };
+        let ticket2 = Ticket {
+            title: title.to_string(),
+            description: "description2".to_string(),
+            status: status.to_string(),
+        };
+        assert_ne!(ticket1, ticket2);
+    }
+
+    #[test]
+    fn test_title_not_matching() {
+        let status = "To-Do";
+        let description = "description";
+        let ticket1 = Ticket {
+            title: "title".to_string(),
+            description: description.to_string(),
+            status: status.to_string(),
+        };
+        let ticket2 = Ticket {
+            title: "title2".to_string(),
+            description: description.to_string(),
+            status: status.to_string(),
+        };
+        assert_ne!(ticket1, ticket2);
+    }
+
+    #[test]
+    fn test_status_not_matching() {
+        let title = "title";
+        let description = "description";
+        let ticket1 = Ticket {
+            title: title.to_string(),
+            description: description.to_string(),
+            status: "status".to_string(),
+        };
+        let ticket2 = Ticket {
+            title: title.to_string(),
+            description: description.to_string(),
+            status: "status2".to_string(),
+        };
+        assert_ne!(ticket1, ticket2);
+    }
+}

src/traits/mod.rs

@@ -0,0 +1,14 @@
+pub mod drop_trait;
+pub mod eight_size_trait;
+pub mod eleven_clone_trait;
+pub mod five_trait_bound;
+pub mod four_derive_trait;
+pub mod nine_from_trait;
+pub mod one_trait;
+pub mod outro_trait;
+pub mod seven_deref_trait;
+pub mod six_str_slice_trait;
+pub mod ten_assos_vs_generic;
+pub mod three_operator_trait;
+pub mod twelve_copy_trait;
+pub mod two_trait;

src/traits/nine_from_trait.rs

@@ -0,0 +1,16 @@
+// TODO: Implement the `From` trait for the `WrappingU32` type to make `example` compile.
+
+pub struct WrappingU32 {
+    value: u32,
+}
+
+impl From<u32> for WrappingU32 {
+    fn from(value: u32) -> Self {
+        Self { value }
+    }
+}
+
+fn example() {
+    let wrapping: WrappingU32 = 42.into();
+    let wrapping = WrappingU32::from(42);
+}

src/traits/one_trait.rs

@@ -0,0 +1,40 @@
+use std::ops::Rem;
+
+// Define a trait named `IsEven` that has a method `is_even` that returns a `true` if `self` is
+// even, otherwise `false`.
+//
+// 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::*;
+
+    #[test]
+    fn test_u32_is_even() {
+        assert!(42u32.is_even());
+        assert!(!43u32.is_even());
+    }
+
+    #[test]
+    fn test_i32_is_even() {
+        assert!(42i32.is_even());
+        assert!(!43i32.is_even());
+        assert!(0i32.is_even());
+        assert!(!(-1i32).is_even());
+    }
+}

src/traits/outro_trait.rs

@@ -0,0 +1,10 @@
+// TODO: Define a new `SaturatingU16` type.
+//   It should hold a `u16` value.
+//   It should provide conversions from `u16`, `u8`, `&u16` and `&u8`.
+//   It should support addition with a right-hand side of type
+//   SaturatingU16, u16, &u16, and &SaturatingU16. Addition should saturate at the
+//   maximum value for `u16`.
+//   It should be possible to compare it with another `SaturatingU16` or a `u16`.
+//   It should be possible to print its debug representation.
+//
+// Tests are located in the `tests` folder—pay attention to the visibility of your types and methods.

src/traits/seven_deref_trait.rs

@@ -0,0 +1,38 @@
+// TODO: whenever `title` and `description` are returned via their accessor methods, they
+//   should be normalized—i.e. leading and trailing whitespace should be removed.
+//   There is a method in Rust's standard library that can help with this, but you won't
+//   find it in the documentation for `String`.
+//   Can you figure out where it is defined and how to use it?
+
+pub struct Ticket {
+    title: String,
+    description: String,
+    status: String,
+}
+
+impl Ticket {
+    pub fn title(&self) -> &str {
+        self.title.as_str().trim()
+    }
+
+    pub fn description(&self) -> &str {
+        self.description.as_str().trim()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_normalization() {
+        let ticket = Ticket {
+            title: "   A title ".to_string(),
+            description: " A description   ".to_string(),
+            status: "To-Do".to_string(),
+        };
+
+        assert_eq!("A title", ticket.title());
+        assert_eq!("A description", ticket.description());
+    }
+}

src/traits/six_str_slice_trait.rs

@@ -0,0 +1,70 @@
+// TODO: Re-implement `Ticket`'s accessor methods. This time return a `&str` rather than a `&String`.
+
+pub struct Ticket {
+    title: String,
+    description: String,
+    status: String,
+}
+
+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");
+        }
+
+        Ticket {
+            title,
+            description,
+            status,
+        }
+    }
+
+    pub fn title(&self) -> &str {
+        &self.title.as_str()
+    }
+
+    pub fn description(&self) -> &str {
+        &self.description.as_str()
+    }
+
+    pub fn status(&self) -> &str {
+        &self.status.as_str()
+    }
+}
+
+mod common {
+    pub fn valid_description() -> String {
+        "fan of a fan".to_string()
+    }
+    pub fn valid_title() -> String {
+        "INDIGO".to_string()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use common::{valid_description, valid_title};
+    use std::any::{Any, TypeId};
+
+    #[test]
+    fn test_type() {
+        let ticket = Ticket::new(valid_title(), valid_description(), "To-Do".to_string());
+        // Some dark magic to verify that you used the expected return types
+        assert_eq!(TypeId::of::<str>(), ticket.title().type_id());
+        assert_eq!(TypeId::of::<str>(), ticket.description().type_id());
+        assert_eq!(TypeId::of::<str>(), ticket.status().type_id());
+    }
+}