wiki/content/20200831155304-methods.md

---
date: 2020-08-31
id: 03a6cd46-e6fb-46a8-96f7-16c37a6d140a
title: Golang methods
---

# Basics

In Go methods can be defined on [struct](20200828181259-structs) and
non-struct types. In this case a **receiver** argument ias passed
between \`func\` keyword and the method name (\`Abs\`):

``` go
package main

import (
    "fmt"
    "math"
)

type Vertex struct {
    X, Y float64
}

func (v Vertex) Abs() float64 {
    return math.Sqrt(v.X*v.X + v.Y*v.Y)
}

func main() {
    v := Vertex{3, 4}
    fmt.Println(v.Abs())
}
```

# Pointers

To modify struct values methods must be declared with pointer receivers:

``` go
package main

import (
    "fmt"
    "math"
)

type Vertex struct {
    X, Y float64
}

func (v Vertex) Abs() float64 {
    return math.Sqrt(v.X*v.X + v.Y*v.Y)
}

func (v *Vertex) Scale(f float64) {
    v.X = v.X * f
    v.Y = v.Y * f
}

func main() {
    v := Vertex{3, 4}
    v.Scale(10)
    fmt.Println(v.Abs())
}
```