goでデザインパターン - Qiita

package main type email struct { from, to, subject, body string } type EmailBuilder struct { email email } func (b *EmailBuilder) From(from string) *EmailBuilder { b.email.from = from return b } func (b *EmailBuilder) To(to string) *EmailBuilder { b.email.to = to return b } func (b *EmailBuilder) Subject(subject string) *EmailBuilder { b.email.subject = subject return b } func (b *EmailBuilder) Bo