From e5779b05c6dd4eb2f855963ea01e569fd2f0438b Mon Sep 17 00:00:00 2001
From: "Rico Sta. Cruz" <rstacruz@users.noreply.github.com>
Date: Fri, 15 Sep 2017 18:01:37 +0800
Subject: [PATCH] go: add methods

---
 go.md | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/go.md b/go.md
index 0baa81d9e..e40bead48 100644
--- a/go.md
+++ b/go.md
@@ -443,6 +443,52 @@ v.X = 2
 
 Doing `v.X` is the same as doing `(*v).X`, when `v` is a pointer.
 
+## Methods
+
+### Receivers
+
+```go
+type Vertex struct {
+  X, Y float64
+}
+```
+
+```go
+func (v Vertex) Abs() float64 {
+  return math.Sqrt(v.X * v.X + v.Y * v.Y)
+}
+```
+{: data-line="1"}
+
+```go
+v: = Vertex{1, 2}
+v.Abs()
+```
+
+There are no classes, but you can define functions with _receivers_.
+
+See: [Methods](https://tour.golang.org/methods/1)
+
+### Mutation
+
+```go
+func (v *Vertex) Scale(f float64) {
+  v.X = v.X * f
+  v.y = v.Y * f
+}
+```
+{: data-line="1"}
+
+```go
+v := Vertex{6, 12}
+v.Scale(0.5)
+// `v` is updated
+```
+
+By defining your receiver as a pointer (`*Vertex`), you can do mutations.
+
+See: [Pointer receivers](https://tour.golang.org/methods/4)
+
 ## References
 
 - [A tour of Go](https://tour.golang.org/welcome/1) _(tour.golang.org)_