ビルダーを利用したオプション引数

builder-option.go

package main

// ビルダーを利用したオプション引数

import "fmt"

type Portion int

const (
	Regular Portion = iota
	Small
	Large
)

type Udon struct {
	men      Portion
	aburaage bool
	ebiten   uint
}

type fluentOpt struct {
	men      Portion
	aburaage bool
	ebiten   uint
}

func (o *fluentOpt) Aburaage() *fluentOpt {
	o.aburaage = true
	return o
}

func (o *fluentOpt) Ebiten(n uint) *fluentOpt {
	o.ebiten = n
	return o
}

func (o *fluentOpt) Order() *Udon {
	return &Udon{
		men:      o.men,
		aburaage: o.aburaage,
		ebiten:   o.ebiten,
	}
}

func NewUdon(p Portion) *fluentOpt {
	return &fluentOpt{
		men:      p,
		aburaage: false,
		ebiten:   1,
	}
}

func main() {
	oomoriKItsune := NewUdon(Large).Aburaage().Order()
	fmt.Printf("%#v\n", oomoriKItsune)
}