Being as DRY as possible in a Ruby on Rails App

class Asset < ActiveRecord::Base
  ... attachment_fu logic ...
end

class Avatar < Asset
  ... avatar specific attachment_fu logic ...
end

class PDF < Asset
  ... PDF specific attachment_fu logic ...
end

class FileUpload < ActiveRecord::Base
      belongs_to :fileable, :polymorphic => true
      file_column :name
    end

class Company < ActiveRecord::Base
      has_many :file_uploads, :as => :fileable
    end