# app/models/concerns/memoizable.rb
module Memoizable
  extend ActiveSupport::Concern

  class_methods do
    def memoize(*method_names)
      method_names.each do |method_name|
        memoized_ivar = "@_memoized_#{method_name.to_s.sub(/\?\Z/, '_query').sub(/!\Z/, '_bang')}".to_sym
        memoized_module = Module.new do
          module_eval <<-EVAL
            def #{method_name}
              unless #{memoized_ivar}
                #{memoized_ivar} = [super]
              end
              #{memoized_ivar}[0]
            end

            def reload
              #{memoized_ivar} = nil
              super
            end

            def self.to_s
              "Memoizable::MemoizedMethod(#{method_name})"
            end

            def self.inspect; to_s; end
          EVAL
        end
        prepend memoized_module
      end
    end
  end
end