Ruby类和实例变量跨继承生命周期演示

Posted 2021-02-24

require 'logger'
$log = Logger.new(STDOUT)
$log.level = Logger::INFO
$log.progname = "LifecycleDemo"
$log.formatter = proc { |severity, datetime, progname, msg|
    #"#{datetime.strftime("%Y-%b-%d %a %H:%M")} #{severity} #{progname} {#{msg}}
"
    "#{msg}
"
  }
#$log.datetime_format = "%a %Y-%m-%d %H:%M"
 
 
class FirstClass
  @@grandClass = "FirstClassVar" # class level variable to track
  def initialize
    @grandVar = "FirstInstanceVar" # instance variable to track
    $log.info("! FirstClass init, #{ids}")
  end
  def grand
    $log.info("> FirstClass grand, #{ids}")
  end
 
  def ids
      "#{self.class.name}:: #{@@grandClass}:#{@@grandClass.object_id}, #{@grandVar}:#{@grandVar.object_id}"
  end
end
 
class SecondClass < FirstClass
  def initialize
    @ego_hilite = "-" * 15
    super
    $log.info("! Second class init, #{ids}")
  end
  def spill_it
    $log.info("> Spill It call, #{ids}")
  end
  def alter_ego
      @grandVar = "SecondInstanceVar"
      @@grandClass = "SecondClassVar"
      $log.info("
#{@ego_hilite} Ego altered by the #{self.class.name} #{@ego_hilite}

")
  end
end
 
class ThirdClass < SecondClass
  @@grandClass = "ThirdClassStatic"
  def initialize
    super
    $log.info("! 3rd class init, #{ids}")
  end
  def alter_ego
      @grandVar = "ThirdInstanceVar"
      @@grandClass = "ThirdClassVar"
      $log.info("
#{@ego_hilite} Ego altered by the Third Class #{@ego_hilite}
")
  end
end
 
def test(instance)
    hilite = "*" * 20
    $log.info("

#{hilite} Testing instance of #{instance.class.name} BEGIN #{hilite}")
    instance.grand
    instance.spill_it
 
    # see what gets changed if anything:
    instance.alter_ego
 
    instance.grand
    instance.spill_it
    $log.info("
#{hilite} Testing instance of #{instance.class.name} END #{hilite}")
end
 
test(SecondClass.new)
test(ThirdClass.new)