How to use ActiveSupport's class_attribute to get sane, overridable class attributes in Ruby.

parenty.rb

class Parenty
  class_attribute :foo
  self.foo = 123

  def self.printy
    "Hello #{self.foo}"
  end
end

class Childy < Parenty
  self.foo = 456
end

puts Parenty.foo
puts Childy.foo
puts Parenty.printy
puts Childy.printy

# Output:
# 123
# 456
# Hello 123
# Hello 456