Question

I have a class (ActorClue) that has three attr_accessor defined within it. There are a couple other common fields needed by other classes, so I put those common fields in a module (BaseClueProperties). I am including that module within my ActorClue class.

Here’s the code sampling :

module BaseClueProperties  
  attr_accessor :image_url
  attr_accessor :summary_text  
end

################
class BaseClue

  # http://stackoverflow.com/questions/2487333/fastest-one-liner-way-to-list-attr-accessors in-ruby    
  def self.attr_accessor(*vars)
    @attributes ||= []

    @attributes.concat vars

    super(*vars)
  end

  def self.attributes
    @attributes
  end

  def attributes
    self.class.attributes
  end

end

###############

class ActorClue < BaseClue

  attr_accessor :actor_name
  attr_accessor :movie_name
  attr_accessor :directed_by

  include BaseClueProperties

  .....
end

I instantiate the above with the following :

>> gg = ActorClue.new
=> #<ActorClue:0x23bf784>
>> gg.attributes
=> [:actor_name, :movie_name, :directed_by] 

Why is it only returning :actor_name, :movie_name, and :directed_by and not include :image_url and :summary_text?

I modified the BaseClueProperties to read the following :

module BaseClueProperties  
  BaseClue.attr_accessor :image_url
  BaseClue.attr_accessor :summary_text  
end

But still with the same result.

Any thoughts as to why my :image_url and :summary_text attributes aren’t getting added to my @attributes collection?

Answer 1

I can’t promise that my description of the reason is correct but the following code should fix the problem. I believe that your are adding attributes to the Module not to the class that it is included within. Anyhow replacing your module with the following should fix the problem.

module BaseClueProperties

  def self.included(base)
    base.send :attr_accessor, :image_url
    base.send :attr_accessor, :summary_text
  end

end 

This should cause the including object to define attribute_accessors when it includes the module.