Differences with Rails 2.3 class_inheritable_accessor and Rails 3.2+ class_attribute

class_inheritable_accessor_vs_class_attribute_differences.rb

class Task
  class_inheritable_accessor :foo
  self.foo = []

  class_attribute :bar
  self.bar = []
end

class Subtask < Task
end

Task.foo.object_id == Subtask.foo.object_id
# => false

Task.bar.object_id == Subtask.bar.object_id
# true

Task.foo << 'hi'
Subtask.foo << 'bye'
Task.foo # => ['hi']
Subtask.foo # => ['bye']

Task.bar << 'hi'
Subtask.bar << 'bye'
Task.bar # => ['hi', 'bye']
Subtask.bar # => ['hi', 'bye']

=begin
`foo` gets dup’d when subclasses so each class gets its own copy of an 
empty array whereas `bar`inherits the same reference by the default.
=end