2 files changed, 97 insertions, 0 deletions
diff --git a/rust-book/oop/src/lib.rs b/rust-book/oop/src/lib.rs
new file mode 100755
index 0000000..91ef2e8
--- /dev/null
+++ b/rust-book/oop/src/lib.rs
@@ -0,0 +1,41 @@
+pub trait Draw {
+    fn draw(&self);
+}
+
+pub struct Screen {
+    pub components: Vec<Box<dyn Draw>>,
+}
+
+impl Screen {
+    pub fn run(&self) {
+        for component in self.components.iter() {
+            component.draw();
+        }
+    }
+}
+
+pub struct Button {
+    pub width: u32,
+    pub height: u32,
+    pub label: String,
+}
+
+impl Draw for Button {
+    fn draw(&self) {
+        dbg!("drew button");
+    }
+}
+
+pub struct SelectBox {
+    pub width: u32,
+    pub height: u32,
+    pub options: Vec<String>,
+}
+
+impl Draw for SelectBox {
+    fn draw(&self) {
+        dbg!("drew select box");
+    }
+}
+
+
diff --git a/rust-book/oop/src/main.rs b/rust-book/oop/src/main.rs
new file mode 100755
index 0000000..e92c07c
--- /dev/null
+++ b/rust-book/oop/src/main.rs
@@ -0,0 +1,56 @@
+use oop::{Screen, Button, SelectBox};
+
+pub struct AveragedCollection {
+    list: Vec<i32>,
+    average: f64,
+}
+
+impl AveragedCollection {
+    pub fn add(&mut self, value: i32) {
+        self.list.push(value);
+        self.update_average();
+    }
+
+    pub fn remove(&mut self) -> Option<i32> {
+        let result = self.list.pop();
+        match result { 
+            Some(value) => {
+                self.update_average();
+                Some(value)
+            },
+            None => None,
+        }
+    }
+
+    pub fn average(&self) -> f64 {
+        self.average
+    }
+
+    fn update_average(&mut self) {
+        let total: i32 = self.list.iter().sum();
+        self.average = total as f64 / self.list.len() as f64;
+    }
+}
+
+fn main() {
+    let screen = Screen {
+        components: vec![
+            Box::new(SelectBox {
+                width: 75,
+                height: 10,
+                options: vec![
+                    String::from("Yes"),
+                    String::from("Maybe"),
+                    String::from("No")
+                ],
+            }),
+            Box::new(Button {
+                width: 50,
+                height: 10,
+                label: String::from("OK"),
+            }),
+        ],
+    };
+
+    screen.run();
+}