self_vars.rb

class ParentClass
  puts "Self when defining ParentClass: #{self.class} / #{self.inspect}"
  def parent_method
    puts "Self inside parent_method: #{self.class} / #{self.inspect}"
  end
end

module MyModule
  def self.module_obj_method
    puts "Self inside module_obj_method: #{self.class} / #{self.inspect}"
  end

  def module_inst_method
    puts "Self inside module_inst_method: #{self.class} / #{self.inspect}"
  end
end

class AClass < ParentClass
  include MyModule

  def self.class_method
    puts "Self inside AClass's class_method: #{self.class} / #{self.inspect}"
  end

  def instance_method
    puts "Self inside AClass's instance_method: #{self.class} / #{self.inspect}"
  end
end

AClass.class_method
MyModule.module_obj_method
a = AClass.new
a.instance_method
a.parent_method
a.module_inst_method

class << a
  puts "Self while defining eigenclass: #{self.class} / #{self.inspect}"
  def self.eigenclass_method
    puts "Self inside eigenclass_method: #{self.class} / #{self.inspect}"
  end

  def eigenclass_instance_method
    puts "Self inside eigenclass_instance_method: #{self.class} / #{self.inspect}"
  end
end

puts "At-at variables:"

class ParentClass
  @@var = "Parent class var"
end

class AClass
  @@var = "Child class var"
end

class ParentClass
  puts "Parentclass @@var: #{@@var.inspect}"
end

class AClass
  puts "Child class @@var: #{@@var.inspect}"
end