Add traits exercise

Cargo.toml

@@ -7,5 +7,6 @@ members = [
     "example/puzzles",
     "exercise/idiomatic",
     "exercise/docs",
-    "exercise/closures_iterators"
+    "exercise/closures_iterators",
+    "exercise/traits"
 ]

exercise/traits/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "traits"
+version = "0.1.0"
+authors = ["Nathan Stocks <nathan@agileperception.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

exercise/traits/src/main.rs

@@ -0,0 +1,88 @@
+pub enum Cake {
+    Chocolate,
+    MapleBacon,
+    Spice,
+}
+
+pub struct Party {
+    pub at_restaurant: bool,
+    pub num_people: u8,
+    pub cake: Cake,
+}
+
+fn main() {
+    // 1. The code below doesn't work because Cake doesn't implement Debug.
+    // - Derive the Debug trait for the Cake enum above so this code will work.
+
+    let cake = Cake::Spice;
+    admire_cake(cake);
+
+    // 2. Uncomment the code below. It doesn't work since `cake` was moved into the admire_cake()
+    // function.
+    // - Derive the Copy trait for the Cake enum so that `cake` gets copied into the
+    //   admire_cake() function instead of moved.
+    // - Hint: You may need to implement an additional trait in order to be able to implement Copy.
+
+    // match cake {
+    //     Cake::Chocolate => println!("The name's Chocolate. Dark...Chocolate."),
+    //     Cake::MapleBacon => println!("Dreams do come true!"),
+    //     Cake::Spice => println!("Great, let's spice it up!"),
+    // }
+
+    // 3. Uncomment the println below
+    // - Derive Debug for the Party struct above
+    // - Manually implement the Default trait for the Party struct above. The default value you
+    //   should return from your trait implementation should be:
+    //
+    //     Party {
+    //         at_restaurant: true,
+    //         num_people: 8,
+    //         cake: Cake::Chocolate,
+    //     }
+    //
+    // Hint: If you get stuck, there is an example at
+    // https://doc.rust-lang.org/std/default/trait.Default.html#how-can-i-implement-default
+
+    // println!("The default Party is\n{:#?}", Party::default());
+
+    // 4. You prefer Maple Bacon cake. Use "struct update syntax" to create a Dessert with `cake`
+    // set to `Cake::MapleBacon`, but the rest of the values are default.
+    //
+    // Hint: The trick to struct update syntax is specifying the value(s) you want to customize and
+    // then ending the struct with `..Default::default()` -- but no comma after that!
+
+    // let party = Party {
+    //     ...
+    // };
+    // println!("Yes! My party has my favorite {:?} cake!", party.cake);
+
+    // 5. Parties are "equal" if they have the same cake.
+    // - Derive the PartialEq trait for the Cake enum so Cakes can be compared.
+    // - Manually implement the PartialEq trait for Party. If different parties have the same cake,
+    // then they are equal.
+    // - Uncomment and run the code below.
+
+    // let other_party = Party {
+    //     at_restaurant: false,
+    //     num_people: 235,
+    //     cake: Cake::MapleBacon,
+    // };
+    // if party == other_party {
+    //     println!("Your party is just like mine!");
+    // }
+
+    // Challenge: You would like to be able to pass a Party struct into the smell_cake() function
+    // which takes a type T which implements the Into<Cake> trait.
+    // - Uncomment the code below AND the smell_cake() function at the bottom of this file
+    // - Implement From<Party> for Cake so that the code below will work.
+
+    // smell_cake(party);
+}
+
+pub fn admire_cake(cake: Cake) {
+    println!("What a nice {:?} cake! 🎂", cake);
+}
+
+// pub fn smell_cake<T: Into<Cake>>(something: T) {
+//     println!("Hmm...something smells like a {:?} cake!", something.into());
+// }