class Pathname
  def non_existing
    dir = dirname
    ext = extname
    name = basename(ext)
    postfix = nil
    while (path = dir + "#{name}#{postfix}#{ext}").exist?
      postfix = postfix ? postfix.succ : '-a'
    end
    path
    # begin
    #   FSPath('abc').open(Fcntl::O_WRONLY | Fcntl::O_CREAT | Fcntl::O_EXCL) do |f|
    #   end
    # rescue => e
    #   p e
    # end

  end

  def lock(options = {}, &block)
    File.lock(@path, options, &block)
    # class File
    #   def self.lock(path, options = {})
    #     if lock = File.open(path, options[:mode] || 'r')
    #       begin
    #         if lock.flock(options[:no_block] ? (File::LOCK_EX | File::LOCK_NB) : (File::LOCK_EX))
    #           yield
    #         end
    #       ensure
    #         lock.flock(File::LOCK_UN)
    #         lock.close
    #       end
    #     end
    #   end
    # end
    # Fcntl::O_RDONLY | Fcntl::O_CREAT
    # Fcntl::O_SHLOCK
    # Fcntl::O_EXLOCK
  end
end