How to marshal an object with open stream, file descriptor or other non serializable data

marshal-logger.rb

#!/usr/bin/ruby

class Logger
  ENDL = "\n".freeze

  def initialize(file_name)
    @file_name = file_name
  end

  def log(message)
    get_stream << message << ENDL
  end

  def close
    # close and catch any error, e.g. from @stream being nil
    @stream.close rescue nil
    @stream = nil
  end

  def marshal_dump
    @stream.flush rescue nil
    @file_name
  end

  def marshal_load(data)
    @file_name = data
  end

private
  def get_stream
    @stream ||= File.open(@file_name, 'a')
  end
end

File.delete "log.txt"
log = Logger.new "log.txt"

log.log "first"
log.log "second"

File.open("log.marshal", 'wb') {|io| Marshal.dump(log, io)}

log.log "third"

log.close # close this as we are overwriting variable log
log = File.open("log.marshal", 'rb') {|io| Marshal.load(io)}

log.log "fourth"
log.close