ruby-on-rails – 包含InstanceMethods模块时覆盖attr_accessor

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

  module ClassMethods
    def has_publish_dates(*args)
      attr_accessor :never_expire

      include InstanceMethods
    end
  end

  module InstanceMethods
    def never_expire=(value)
      @never_expire = ActiveRecord::ConnectionAdapters::Column.value_to_boolean(value)
    end

    def another_instance_method
      'something to return'
    end
  end
end

ActiveSupport.on_load(:active_record) do
  include HasPublishDates
end

可以像这样调用：

class MyModel < ActiveRecord::Base
  has_publish_dates
  ...
end

我们的想法是,never_expire =应该覆盖由attr_accessor：never_expire定义的setter.但是,它似乎没有工作：

m = MyModel.new
m.never_expire            #=> nil
m.never_expire = '1'      #=> '1'
m.never_expire            #=> '1' should be true if never_expire= has been overridden
m.another_instance_method #=> 'something to return' works as expected

正如您所看到的,正在包含another_instance_method并且正在按预期工作但never_expire =并未像我预期的那样覆盖setter.

如果我将HasPublishDates更改为使用class_eval,那么它将按预期工作：

module HasPublishDates
  ...
  module ClassMethods
    def has_publish_dates(*args)
      ...
      class_eval do
        def never_expire=(value)
          @never_expire = ActiveRecord::ConnectionAdapters::Column.value_to_boolean(value)
        end

        def another_instance_method
          'something to return'
        end
      end
    end
  end
end
...

m = MyModel.new
m.never_expire            #=> nil
m.never_expire = '1'      #=> true
m.never_expire            #=> true
m.another_instance_method #=> 'something to return'

我想这是因为InstanceMethods是在attr_accessor之前定义的：never_expire是由has_publish_dates调用的.

虽然我认为class_eval是一种优雅的做事方式,但我也喜欢将我的实例方法暴露给文档的想法,所以当另一个开发人员试图使用我的代码时,没有“魔力”.

无论如何我可以在这种情况下使用include InstanceMethods方法吗？