added point example

Author: BartMassey

README.md

@@ -16,3 +16,4 @@ in a controlled repository now.
 * `readline`: example of readline with error handling
 * `error`: example of creating a custom error
 * `modules`: example of Rust modules
+* `point.rs`: example of Rust "methods" and ownership

point.rs

@@ -0,0 +1,33 @@
+#[derive(Debug)]
+struct Point {
+    x: i64,
+    y: i64,
+}
+
+impl Point {
+    fn new(x: i64, y: i64) -> Point {
+        Point{ x, y }
+    }
+    
+    fn flip(&mut self) {
+        let tmp = self.x;
+        self.x = self.y;
+        self.y = tmp;
+    }
+    
+    fn flipped(&self) -> Point {
+        Point{ x: self. y, y: self. x }
+    }
+    
+    fn collapse(self) -> i64 {
+        self.x + self.y
+    }
+}
+
+fn main() {
+    let mut p = Point::new(3, 4);
+    println!("{:?}", p.flipped());
+    p.flip();
+    println!("{:?}", p);
+    println!("{}", p.collapse());
+}