Response to TvL2386 on the #ruby IRC channel

main_truck.rb

require 'psych'

class MailTruck
  attr_accessor :driver, :route

  def initialize driver:, route:, speed: 0
    @driver = driver
    @route = route
    @speed = speed
  end

  def encode_with coder
    coder['driver'] = @driver
    coder['route'] = @route
  end

  def _dump _
    Marshal.dump({driver: @driver, route: @route})
  end

  class << self
    def init_with coder
      @driver = coder['driver']
      @route = coder['route']
    end

    def _load s
      new **Marshal.load(s)
    end
  end
end

truck = MailTruck.new(
  driver: 'Harold',
  route: ['12 Corrigan Way', '23 Antler Ave']
)

yaml = truck.to_yaml

puts yaml
#>> --- !ruby/object:MailTruck
#>> driver: Harold
#>> route:
#>> - 12 Corrigan Way
#>> - 23 Antler Ave

Psych.load yaml
#=> #<MailTruck:... @driver="Harold", @route=["12 Corrigan Way", "23 Antler Ave"]>

marshal = Marshal.dump truck
#=> "\x04\bu:\x0EMailTruckR\x04\b{\a:\vdriverI\"\vHarold\x06:\x06ET:\nroute[\aI\"\x1412 Corrigan Way\x06;\x06TI\"\x1223 Antler Ave\x06;\x06T"

Marshal.load marshal
#=> #<MailTruck:0x000000010a1dfc58 @driver="Harold", @route=["12 Corrigan Way", "23 Antler Ave"], @speed=0>