create

# File actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 530
          def self.create(template, controller, source, include_host = true)
            CacheGuard.synchronize do
              key = if controller.respond_to?(:request)
                [self, controller.request.protocol,
                 ActionController::Base.asset_host,
                 ActionController::Base.relative_url_root,
                 source, include_host]
              else
                [self, ActionController::Base.asset_host, source, include_host]
              end
              Cache[key] ||= new(template, controller, source, include_host).freeze
            end
          end