如何在插件中保存回调之前在其中包含实例方法?

我正在创建一个插件,很难定义一个调用我刚刚定义的实例方法的“保存前”过滤器。下面是一个快速的示例:

module ValidatesAndFormatsPhones
  def self.included(base)
    base.send :extend, ClassMethods
  end

  module ClassMethods

    def validates_and_formats_phones(field_names = [:phone])
      send :include, InstanceMethods

      # the following variations on calls to :format_phone_fields fail

      before_save send(:format_phone_fields, field_names)

      before_save format_phone_fields(field_names)

      before_save lambda { send(:format_phone_fields, field_names) }

      # EACH OF THE ABOVE RETURNS 'undefined_method :format_phone_fields'
    end
  end

  module InstanceMethods

    def format_phone_fields(fields = [:phone], *args)
      do stuff...
    end

  end
end

ActiveRecord::Base.send :include, ValidatesAndFormatsPhones

我想问题是,如何将上下文更改为实例,而不是类?

我更喜欢调用实例方法,因为类不应该真正有一个名为“format\phone\u fields”的方法,但实例应该有。

谢谢!