Configurable provides a config method to store and retrieve configuration options as an OrderedHash.

Namespace
Methods
C
Instance Public methods
config()

Reads and writes attributes from a configuration OrderedHash.

require 'active_support/configurable'

class User
  include ActiveSupport::Configurable
end

user = User.new

user.config.allowed_access = true
user.config.level = 1

user.config.allowed_access # => true
user.config.level          # => 1

Source: show | on GitHub 

# File activesupport/lib/active_support/configurable.rb, line 85
def config
  @_config ||= self.class.config.inheritable_copy
end