Memoizing in Ruby 2 with prepend

gistfile1.rb

module Memoizable

  def self.extended(mod)
    mod.module_eval{ prepend(@memoizer = Module.new) }
  end

  def memoize(name)
    @memoizer.module_eval do
      define_method(name) do |*args, &block|
        raise(ArgumentError, "cannot memoize method called with block") if block
        @memoized ||= {}
        @memoized[name] ||= {}
        if @memoized[name].has_key?(args)
          @memoized[name][args]
        else
          @memoized[name][args] = super(*args, &block)
        end
      end
    end
  end

end