retrieve_variable

# File actionview/lib/action_view/renderer/partial_renderer.rb, line 474
    def retrieve_variable(path, as)
      variable = as || begin
        base = path[-1] == "/" ? "" : File.basename(path)
        raise_invalid_identifier(path) unless base =~ /\A_?([a-z]\w*)(\.\w+)*\z/
        $1.to_sym
      end
      variable_counter = :"#{variable}_counter" if @collection
      [variable, variable_counter]
    end