module Immutable
  def self.included(mod)
    mod.extend(ClassMethods)
  end

  module ClassMethods
    def immutable_method(*args)
      args.each do |method|
        alias_method "orig_#{method}", method
      end

      @args = args
      module_eval do
        def self.method_added(sym)
          if @args
            @args.each do |method|
              if method
                if sym == method.to_sym 
                  unless called_by_method_added
                    self.module_eval <<-"end;"
                      def #{method.to_s}(*args, &block)
                        orig_#{method.to_s}(*args, &block)
                      end
                    end;
                  end # called_by_method_added
                end # method.to_sym
              end # method
            end # @args.each
          end # @args
        end # def self.method_added()

        def self.method_undefined(sym)
          method_added(sym)
        end

        def self.method_removed(sym)
          method_added(sym)
        end
      end # module_eval

      def self.called_by_method_added
        # This is a little brittle, suggestions?
        caller[3] =~ /eval.*in.*method_added/
      end
    end # def immutable_method()

    alias immutable_methods immutable_method

  end # module ClassMethods
end # module Immutable