Someone on Ruby-Talk was recently asking about an attr_accessor workalike for Classes. While writing my metaclasses article, I spent a bit of time poking around the goodies in Rails’ active_support directory and came across class_attribute_accessors.rb, which does the business.

After loading the class, use cattr_reader, cattr_writer, and cattr_accessor as you would the instance equivalents.

 class MailTruck
   cattr_accessor :trucks, :customers
 end
 MailTruck.trucks = [:UPS_TRUCK_9189, :UPS_TRUCK_9192]

You can also wield mattr_* methods as well.