Caching a method in Rails

cached_method.rb

module CachedMethod

  def self.included(base)
    base.class_eval do
      @method_cache_validators = Hash.new(0)
      extend ClassMethods
    end
  end

  module ClassMethods
    def invalidate_method_cache(method)
      @method_cache_validators[method.to_sym] += 1
    end

    def cache_marker_for(method)
      @method_cache_validators[method.to_sym]
    end

    def cache_methods(method, expire: 5.minutes, cache_key: lambda { |obj| return obj.cache_key } )
      alias_method :"uncached_#{method}", method.to_sym

      define_method("invalidate_#{method}") do
        self.class.invalidate_method_cache(method)
      end

      define_method(method) do |args=nil|
        puts "cache:#{self.class.cache_marker_for(method)}:#{self.class.name.downcase}:#{cache_key.call(self)}:#{method.to_s}:#{args.to_s}"
        Rails.cache.fetch("cache:#{self.class.cache_marker_for(method)}:#{self.class.name.downcase}:#{cache_key.call(self)}:#{method.to_s}:#{args.to_s}", expires_in: expire) do
          if args
            send(:"uncached_#{method}", args)
          else
            send(:"uncached_#{method}")
          end
        end
      end
    end
  end
end