Clarify instructions for exercise `traits`

subjects/traits/README.md

@@ -4,11 +4,14 @@
 
 Imagine you are designing a new video game and you have to create food that the players can eat to gain strength.
 
-There are two types of food for now, fruits and meat: fruits increase the strength by 1 unit and meat increases it by 3 units.
+There are two types of food for now:
 
-- Define both structures fruits and meat:
+- Fruit: increase the strength by 4 unit per each kilogram of fruit consumed.
+- Meat: has the weight in kilograms -> `weight_in_kg` (which is the weight of the whole piece) and the fat_content which corresponds to the percentage of the weight which is pure fat (the rest is consider protein) each kilogram of protein gives 4 units of `strenght` and each kilogram of fat gives 9 units of `strength`.
 
-Define the std::fmt::Display trait of the Player structure in a way that when using the template {} inside a println! macro it will print:
+Define the `Food` trait for `Fruit` and `Meat`. The method require method `gives()` represents the energy that the food provides.
+
+Implement the `std::fmt::Display` trait for `Player` structure in a way that when using the template `{}` inside a println! macro it will print:
 
 - In the first line, the name of the player
 - In the second line the strength, score and the money
@@ -20,7 +23,7 @@ Define the std::fmt::Display trait of the Player structure in a way that when us
 #[derive(Debug)]
 pub struct Player {
 	pub name: String,
-	pub strength: u32,
+	pub strength: f64,
 	pub score: i32,
 	pub money: i32,
 	pub weapons: Vec<String>,
@@ -54,14 +57,17 @@ impl Food for Meat {
 
 ### Usage
 
-Here is a program to test your function.
+Here is a program to test your functions and traits.
 
 ```rust
-use generics::*;
+use traits::*;
+
 
 fn main() {
 	let apple = Fruit { weight_in_kg: 1.0 };
-	assert_eq!(apple.gives(), 4);
+
+	println!("this apple gives {} units of strength", apple.gives());
+
 	let steak = Meat {
 		weight_in_kg: 1.0,
 		fat_content: 1.0,
@@ -69,27 +75,33 @@ fn main() {
 
 	let mut player1 = Player {
 		name: String::from("player1"),
-		strength: 1,
+		strength: 1.0,
 		score: 0,
 		money: 0,
 		weapons: vec![String::from("knife")],
 	};
 	println!("Before eating {:?}", player1);
 	player1.eat(apple);
-	println!("After eating an apple\n{:?}", player1);
+	println!("After eating an apple\n{}", player1);
 	player1.eat(steak);
-	println!("After eating a steak\n{:?}", player1);
+	println!("After eating a steak\n{}", player1);
 }
+
 ```
 
 And its output:
 
 ```console
 student@ubuntu:~/[[ROOT]]/test$ cargo run
-Before eating Player { name: "player1", strength: 1, score: 0, money: 0, weapons: ["knife"] }
+this apple gives 4 units of strength
+Before eating Player { name: "player1", strength: 1.0, score: 0, money: 0, weapons: ["knife"] }
 After eating an apple
-Player { name: "player1", strength: 5, score: 0, money: 0, weapons: ["knife"] }
+player1
+Strength: 5, Score: 0, Money: 0
+Weapons: ["knife"]
 After eating a steak
-Player { name: "player1", strength: 14, score: 0, money: 0, weapons: ["knife"] }
+player1
+Strength: 14, Score: 0, Money: 0
+Weapons: ["knife"]
 student@ubuntu:~/[[ROOT]]/test$
 ```