function_options.go

package main

import "fmt"

type User struct {
	Name  string
	UID   int
	Menus []string
}

type UserOption func(*User)

func DefaultMenu(m ...string) UserOption {
	return func(s *User) { s.Menus = m }
}

func UID(id int) UserOption {
	return func(s *User) { s.UID = id }
}

func New(options ...UserOption) *User {
	s := &User{Name: "hello"}
	for _, option := range options {
		option(s)
	}

	return s
}

func main() {
	u := New(
		DefaultMenu("a", "b"),
		UID(10),
	)
	fmt.Println(u)
}