retrieve_variable

# File actionview/lib/action_view/renderer/partial_renderer.rb, line 521
    def retrieve_variable(path, as)
      variable = as || begin
        base = path[-1] == "/".freeze ? "".freeze : File.basename(path)
        raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
        $1.to_sym
      end
      if @collection
        variable_counter = :"#{variable}_counter"
        variable_iteration = :"#{variable}_iteration"
      end
      [variable, variable_counter, variable_iteration]
    end