module MemoHelper

# File lib/memo_helper.rb, line 4
def memo(method_name, &block)
  self.class_eval do
    define_method "unmemoized_#{method_name}", block

    define_method method_name do
      inst_var = "@#{method_name}"
      return instance_variable_get(inst_var) if instance_variable_defined?(inst_var)
      instance_variable_set(inst_var, send("unmemoized_#{method_name}"))
    end
  end
end