functional_options_interface.go

package main

import "fmt"

type tableServer struct {
	table int
}

type TableServer interface {
	SetTable(table int)
	GetTable() int
}

func NewTableServer() TableServer {
	return &tableServer{}
}

func (i *tableServer) SetTable(table int) {
	i.table = table
}

func (i *tableServer) GetTable() int {
	return i.table
}

func SetTable(table int) func(TableServer) {
	return func(i TableServer) {
		i.SetTable(table)
	}
}

type Waiter struct {
	Name string
	TableServer
}

func NewWaiter(name string, options ...func(TableServer)) *Waiter {
	w := &Waiter{
		Name:        name,
		TableServer: NewTableServer(),
	}

	for _, option := range options {
		option(w)
	}

	return w
}

type Host struct {
	Name string
	TableServer
}

func NewHost(name string, options ...func(TableServer)) *Host {
	w := &Host{
		Name:        name,
		TableServer: NewTableServer(),
	}

	for _, option := range options {
		option(w)
	}

	return w
}

func main() {
	waiter := NewWaiter("joe")
	fmt.Println(waiter.Name, "is working table", waiter.GetTable())

	waiter = NewWaiter("bob", SetTable(9))
	fmt.Println(waiter.Name, "is working table", waiter.GetTable())

	host := NewHost("tom", SetTable(3))
	fmt.Println(host.Name, "is working table", host.GetTable())
}