# File lib/nanoc3/base/filter.rb, line 114
    def output_filename
      @output_filename ||= begin
        require 'tempfile'

        FileUtils.mkdir_p(TMP_BINARY_ITEMS_DIR)
        tempfile = Tempfile.new(filename.gsub(/[^a-z]/, '-'), TMP_BINARY_ITEMS_DIR)
        new_filename = tempfile.path
        tempfile.close!

        new_filename
      end
    end