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Ruby class and instance variables lifecycle across inheritance demo

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  1. require 'logger'
  2. $log = Logger.new(STDOUT)
  3. $log.level = Logger::INFO
  4. $log.progname = "LifecycleDemo"
  5. $log.formatter = proc { |severity, datetime, progname, msg|
  6.     #"#{datetime.strftime("%Y-%b-%d %a %H:%M")} #{severity} #{progname} {#{msg}}\n"
  7.     "#{msg}\n"
  8.   }
  9. #$log.datetime_format = "%a %Y-%m-%d %H:%M"
  10.  
  11.  
  12. class FirstClass
  13.   @@grandClass = "FirstClassVar" # class level variable to track
  14.   def initialize
  15.     @grandVar = "FirstInstanceVar" # instance variable to track
  16.     $log.info("! FirstClass init, #{ids}")
  17.   end
  18.   def grand
  19.     $log.info("> FirstClass grand, #{ids}")
  20.   end
  21.  
  22.   def ids
  23.       "#{self.class.name}:: #{@@grandClass}:#{@@grandClass.object_id}, #{@grandVar}:#{@grandVar.object_id}"
  24.   end
  25. end
  26.  
  27. class SecondClass < FirstClass
  28.   def initialize
  29.     @ego_hilite = "-" * 15
  30.     super
  31.     $log.info("! Second class init, #{ids}")
  32.   end
  33.   def spill_it
  34.     $log.info("> Spill It call, #{ids}")
  35.   end
  36.   def alter_ego
  37.       @grandVar = "SecondInstanceVar"
  38.       @@grandClass = "SecondClassVar"
  39.       $log.info("\n#{@ego_hilite} Ego altered by the #{self.class.name} #{@ego_hilite}\n\n")
  40.   end
  41. end
  42.  
  43. class ThirdClass < SecondClass
  44.   @@grandClass = "ThirdClassStatic"
  45.   def initialize
  46.     super
  47.     $log.info("! 3rd class init, #{ids}")
  48.   end
  49.   def alter_ego
  50.       @grandVar = "ThirdInstanceVar"
  51.       @@grandClass = "ThirdClassVar"
  52.       $log.info("\n#{@ego_hilite} Ego altered by the Third Class #{@ego_hilite}\n")
  53.   end
  54. end
  55.  
  56. def test(instance)
  57.     hilite = "*" * 20
  58.     $log.info("\n\n#{hilite} Testing instance of #{instance.class.name} BEGIN #{hilite}")
  59.     instance.grand
  60.     instance.spill_it
  61.  
  62.     # see what gets changed if anything:
  63.     instance.alter_ego
  64.  
  65.     instance.grand
  66.     instance.spill_it
  67.     $log.info("\n#{hilite} Testing instance of #{instance.class.name} END #{hilite}")
  68. end
  69.  
  70. test(SecondClass.new)
  71. test(ThirdClass.new)

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