added file to play with methods

methods/methods.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+    "fmt"
+)
+
+type vertex struct {
+    x, y float64
+}
+
+// note that this one can deal fine with a copy:
+func (v vertex) abs() float64 {
+    return v.x + v.y
+}
+
+// but this function needs access to the actual struct members
+func (v *vertex) scale(s float64) {
+    v.x *= s
+    v.y *= s
+}
+
+func main() {
+    v := vertex{1.1, 2.2}
+    fmt.Println(v.abs())
+    v.scale(12)
+    fmt.Println(v.abs())
+}