supertrait

src/main.rs

@@ -1,4 +1,5 @@
 use std::ops::Add;
+use std::fmt;
 
 #[derive(Debug, PartialEq)]
 struct Point {
@@ -17,7 +18,6 @@ impl Add for Point {
     }
 }
 
-
 #[derive(Debug, PartialEq)]
 struct Millimeters(u32);
 #[derive(Debug, PartialEq)]
@@ -77,6 +77,28 @@ impl Animal for Dog {
     }
 }
 
+
+trait OutlinePrint: fmt::Display {
+    fn outline_print(&self) {
+        let output = self.to_string();
+        let len = output.len();
+
+        println!("{}", "*".repeat(len + 4));
+        println!("*{}*", " ".repeat(len + 2));
+        println!("* {} *", output);
+        println!("*{}*", " ".repeat(len + 2));
+        println!("{}", "*".repeat(len + 4));
+    }
+}
+
+impl fmt::Display for Point {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "({}, {})", self.x, self.y)
+    }
+}
+
+impl OutlinePrint for Point {}
+
 fn main() {
     assert_eq!(
             Point { x: 1, y: 0 } + Point { x: 2, y: 3 },
@@ -94,4 +116,8 @@ fn main() {
     Wizard::fly(&person);
     
     println!("A baby dog is called a {}", <Dog as Animal>::baby_name());
+    
+    let xy = Point { x: 344, y: 576 };
+    xy.outline_print();
+    println!("{}", Point {x: 34, y:45})
 }