Sometimes, you need a config-like property on a class, such as a logger. Rails provides a `Configurable` concern that lets you accomplish this. It provides a
config method that allows you to access (read and write) configuration options using the method-like syntax.
class Invoice include ActiveSupport::Configurable config_accessor :type end Invoice.type # => nil Invoice.type = :cheque Invoice.type # => :cheque
A nice benefit of using
Configurable is that all the instances get the same config option, which they can override independently without affecting the class config.
invoice = Invoice.new invoice.type # => :cheque invoice.type = :credit invoice.type # => :credit Invoice.type # => :cheque new_invoice = Invoice.new new_invoice.type # => :cheque
Behind the scenes, the
config method returns an instance of
OrderedOptions class. To learn more, check out my article on ordered options.
Rails uses the
Configurable concern to add
logger configuration option on the controllers.
AbstractController::Base class includes this concern so you can configure a logger on the controllers.
# actionpack/lib/abstract_controller/base.rb require "active_support/configurable" module AbstractController class Base include ActiveSupport::Configurable # rest of the code end end end
AbstractController::Logger module (concern) configures the
:logger config on the controllers.
# actionpack/lib/abstract_controller/logger.rb module AbstractController module Logger extend ActiveSupport::Concern included do config_accessor :logger end end end
This allows you to configure loggers on your controllers, as well as access them whenever needed.
To learn more about concerns and how they work, check out this detailed article.