enum: Add full example with match - access specific type params

enum_example/src/main.rs

@@ -17,7 +17,16 @@ enum Message {
 
 impl Message {
     fn print(&self) {
-        println!("calling message {:?}", self);
+        println!("I don't do anything but can be called with any type: {:?}", self);
+    }
+
+    fn call(&self) {
+        match self {
+	    Message::Quit => println!("Calling on a quit type!"),
+	    Message::Move { x, y } => println!("Calling on a move type: {}, {}!", x, y),
+	    Message::Write (s) => println!("Calling on a write type: {}!", s),
+	    Message::ChangeColor (c) => println!("Calling on a color type: {:#?}!", c),
+	}
     }
 }
 
@@ -29,10 +38,14 @@ fn main() {
 
     let msg = Message::Quit;
     msg.print();
+    msg.call();
     let msg = Message::Move{ x: 1, y:2};
     msg.print();
+    msg.call();
     let msg = Message::Write(String::from("Hello enum"));
     msg.print();
+    msg.call();
     let msg = Message::ChangeColor(Color(1,2,3));
     msg.print();
+    msg.call();
 }