class Utils::Finder

def index_path
  roots = @roots.map { |r| File.expand_path(r) }.uniq.sort
  filename = "finder-paths-" +
    Digest::MD5.new.update(roots.inspect).hexdigest
  dirname = File.join(Dir.tmpdir, File.basename($0))
  FileUtils.mkdir_p dirname
  File.join(dirname, filename)
end