gistfile1.txt

module Datastores
  module Memoizable
    extend ActiveSupport::Concern
    include ThreadLocal

    KEY_REGEX = /`([^']*)'/

    module ClassMethods

      def memoize(key = nil, &block)
        key = (key || caller[0][KEY_REGEX, 1]).to_s.gsub("?", "_question_mark")
        if thread_local.has_key?(key)
          thread_local[key]
        else
          thread_local[key] = block.call
        end
      end

    end

    def memoize(key = nil, &block)
      # It is super important to call Kernel.caller instead of just #caller,
      # because #caller is not defined for delegate classes; method missing
      # will be invoked which will call #memoize on the delegatee and then
      # #caller[0] will be 'method_missing'.
      key = "@" + (key || Kernel.caller[0][KEY_REGEX, 1]).to_s.gsub("?", "_question_mark")
      if instance_variable_defined?(key)
        instance_variable_get(key)
      else
        instance_variable_set(key, block.call)
      end
    end

  end
end