# File lib/nanoc/extra/file_proxy.rb, line 23
    def method_missing(sym, *args, &block)
      if !@@deprecation_warning_shown
        $stderr.puts 'WARNING: The :file attribute is deprecated and will be removed in a future version of nanoc. Instead of using this :file attribute, consider manually creating a File object when it’s needed, using the :content_filename, :meta_filename or :filename attributes.'
        @@deprecation_warning_shown = true
      end

      File.open(@path, 'r') { |io| io.__send__(sym, *args, &block) }
    end