gistfile1.rb

require 'rubygems'
require 'active_support'

class Base
  class_inheritable_accessor :name
  
  self.name = "Base"
    
end

class Foo < Base
  self.name = "Foo"
  
end

f = Foo.new
puts f.name
b = Base.new
puts b.name

# Foo
# Foo

module Scenarios

  class ScenarioError < StandardError
     class_inheritable_accessor :messages
     
     self.messages = {
       :foo => lambda { "bar" }
     }
     
     def initialize(message_key, *args)
      super(messages[message_key].call(*args))
     end
  end
  
  class FooError < ScenarioError
    self.messages.merge!({:bar => lambda { "foo"}})
  end
end

#raise Scenarios::FooError.new(:bar)
p Scenarios::FooError.messages.inspect
raise Scenarios::FooError.new(:foo)