# File lib/linecache.rb, line 213
  def cache_file(filename, reload_on_change=false, opts={})
    if @@file_cache.member?(filename)
      checkcache(filename) if reload_on_change
    else
      opts[:use_script_lines] = true
      update_cache(filename, opts)
    end
    if @@file_cache.member?(filename)
      @@file_cache[filename].path
    else
      nil
    end
  end