Function vs Method

Method ada kepemilikan. Contohnya :

type test int

// function
func Calculate() {}

// method
func (t test) Calculate() {}

Contoh code method

package main

import "fmt"

type rect struct {
	width, height int
}

func (r rect) area() int {
	return r.width * r.height
}

func (r rect) perimeter() int {
	return 2 * (r.width + r.height)
}

func main() {
	r := rect{width: 10, height: 5}
	fmt.Println("area     : ", r.area())
	fmt.Println("perimeter: ", r.perimeter())
}

area     :  50
perimeter:  30

Reference:

Methods in Golang - GeeksforGeeksGeeksforGeeks