@@y = 1
class MyClass
 @@y = 2
end
p @@y # => 2

class Foo
  @@x = 1
end

class Bar
  @@x = 2
end

Foo.class_variable_get(:@@x) # => 1
Bar.class_variable_get(:@@x) # => 2

class Foo
  @@x = 1
end

class Bar < Foo
  @@x = 2
end

Foo.class_variable_get(:@@x) # => 2
Bar.class_variable_get(:@@x) # => 2

@@y = 1
class MyClass
  @@y = 2
end
p @@y

@@y = 1

@@y = 1
class MyClass
  @@y = 2
end
p @@y
puts MyClass.superclass #=> Object
puts Object.class_variables #=> @@y

$y = 1

@@y = 1