fop.go

package main

import(
	"fmt"
	"time"
)

func main() {
	var (
		o []Option
		id string = "idだよ"
		email string = "emailだよ"
	)
	if id != "" {
		o = append(o, WithUserId(id))
	}
	if email != "" {
		o = append(o, WithEmail(email))
	}

	s := NewSearchQuery(o...)
	fmt.Println(s)
}

type SearchQuery struct {
	userId string
	email string
	kind []int
	from time.Time
	to time.Time
}

func GenerateSearchQuery() *SearchQuery {
	return &SearchQuery{}
}

func NewSearchQuery(options ...Option) *SearchQuery {
	s := GenerateSearchQuery()
	for _, f := range options {
		f(s)
	}
	return s
}
type Option func(s *SearchQuery)

func WithUserId(u string) Option {
	return func(s *SearchQuery){
		s.userId = u
	}
}
func WithEmail(e string) Option {
	return func(s *SearchQuery){
		s.email = e
	}
}