stylesheet_link_tag (ActionView::Helpers::AssetTagHelper)

    # File lib/action_view/helpers/asset_tag_helper.rb, line 422
          def stylesheet_link_tag(*sources)
            options = sources.extract_options!.stringify_keys
            concat  = options.delete("concat")
            cache   = concat || options.delete("cache")
            recursive = options.delete("recursive")

            if concat || (ActionController::Base.perform_caching && cache)
              joined_stylesheet_name = (cache == true ? "all" : cache) + ".css"
              joined_stylesheet_path = File.join(joined_stylesheet_name[/^#{File::SEPARATOR}/] ? ASSETS_DIR : STYLESHEETS_DIR, joined_stylesheet_name)

              unless ActionController::Base.perform_caching && File.exists?(joined_stylesheet_path)
                write_asset_file_contents(joined_stylesheet_path, compute_stylesheet_paths(sources, recursive))
              end
              stylesheet_tag(joined_stylesheet_name, options)
            else
              expand_stylesheet_sources(sources, recursive).collect { |source| stylesheet_tag(source, options) }.join("\n")
            end
          end