# File lib/paperclip/storage/fog.rb, line 35
      def self.extended base
        begin
          require 'fog'
        rescue LoadError => e
          e.message << " (You may need to install the fog gem)"
          raise e
        end unless defined?(Fog)

        base.instance_eval do
          unless @options[:url].to_s.match(/^:fog.*url$/)
            @options[:path]  = @options[:path].gsub(/:url/, @options[:url])
            @options[:url]   = ':fog_public_url'
          end
          Paperclip.interpolates(:fog_public_url) do |attachment, style|
            attachment.public_url(style)
          end unless Paperclip::Interpolations.respond_to? :fog_public_url
        end
      end