Tour of Go 2.0

Methods

Go has no classes — but it does have methods.

A method is just a function with a special receiver argument. The receiver sits between the func keyword and the method name, binding the function to a specific type.

In this example, Abs has a receiver of type Vertex named v. That’s what makes it a method instead of a plain function.

Try it: run the code and see Abs() called on v like v.Abs().

main.go ▶ Run in Playground 
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())
}