What is green may not always be grue

customer_notifier_v1.rb

class CustomerNotifier
  def initialize(mail_server, templates)
    @mail_server = mail_server
    @templates = templates
  end

  def confirm_order(customer, data)
    @mail_server.send_mail(customer.email_address, @templates[:confirm_order].render(data))
  end

  def password_reset(customer, data)
    @mail_server.send_mail(customer.email_address, @templates[:password_reset].render(data))
  end
end

customer_notifier_v2.rb

class CustomerNotifier
  def initialize(mail_server, templates)
    @mail_server = mail_server
    @templates = templates
  end

  def send_template(template, customer, data)
    @mail_server.send_mail(customer.email_address, @templates[template].render(data))
  end
end

customer_notifier_v3.rb

class CustomerNotifier
  def initialize(mail_server, templates)
    @mail_server = mail_server
    @templates = templates
  end

  ASYNC_TEMPLATES = %i[promo_code]

  def send_template(template, customer, data)
    if ASYNC_TEMPLATES.include?(template)
      AsyncEmail.create!(customer: customer, data: data)
    else
      @mail_server.send_mail(customer.email_address, @templates[template].render(data))
    end
  end
end

gem_registrar_v1.rb

class GemRegistrar
  def initialize(grs_client)
    @grs_client = grs_client
  end

  def register_emerald
    id = @grs_client.register_gem(
      type: 'emerald',
      color: 'green'
    )

    Gemstone.create!(registration_id: id, type: 'emerald', color: 'green')
  end

  def register_ruby
    id = @grs_client.register_gem(
      type: 'ruby',
      color: 'red'
    )

    Gemstone.create!(registration_id: id, type: 'ruby', color: 'red')
  end
end

gem_registrar_v2.rb

class GemRegistrar
  def initialize(grs_client)
    @grs_client = grs_client
  end

  def register_gem(type, color)
    id = @grs_client.register_gem(
      type: type,
      color: color
    )

    Gemstone.create!(registration_id: id, type: type, color: color)
  end
end