process_asset.rb

module ProcessAsset
  def self.included(base)
    base.extend ClassMethods
  end

  module InstanceMethods
    def process
      self.send("#{asset_name}_file_name")
    end
  end
  
  module ClassMethods
    def process_asset(asset_name)
      include InstanceMethods
      
      define_method :asset_name do
        "#{asset_name}"
      end
    end
  end
end

class Person
  include ProcessAsset
  process_asset :photo
  
  def photo_file_name
    "testing.jpg"
  end
end


p = Person.new
puts p.process #=> testing.jpg