class Design < ActiveRecord::Base
  belongs_to :designable, :polymorphic => true, :touch => true

  def width
    600
  end

  def height
    600
  end
end

## How to override width/height when design is associated? Smth like this:

class Tee < ActiveRecord::Base
  has_one :front_design, :class_name => 'Design', :as => 'designable' do
    def proxy_target.width
      400
    end

    def proxy_target.height
      500
    end
  end
end