Add an example for struct visibility

restaurant/src/lib.rs

@@ -17,6 +17,20 @@ mod front_of_house {
 }
 
 mod back_of_house {
+    pub struct Breakfast {
+        pub toast: String,
+        seasonal_fruit: String,
+    }
+
+    impl Breakfast {
+        pub fn summer(toast: &str) -> Breakfast {
+            Breakfast {
+                toast: String::from(toast),
+                seasonal_fruit: String::from("peaches"),
+            }
+        }
+    }
+
     fn fix_incorrect_order() {
         cook_order();
         super::deliver_order();
@@ -26,9 +40,13 @@ mod back_of_house {
 }
 
 pub fn eat_at_restaurant() {
-    // Absolute path
-    crate::front_of_house::hosting::add_to_waitlist();
+    // Order a breakfast in the summer with Rye toast
+    let mut meal = back_of_house::Breakfast::summer("Rye");
+    // Change our mind about what bread we'd like
+    meal.toast = String::from("Wheat");
+    println!("I'd like {} toast please", meal.toast);
 
-    // Relative path
-    front_of_house::hosting::add_to_waitlist();
+    // The next line won't compile if we uncomment it; we're not allowed
+    // to see or modify the seasonal fruit that comes with the meal
+    // meal.seasonal_fruit = String::from("blueberries");
 }