Ruby on Rails latest stable (v6.1.7.7) - 4 notes - Class: ActiveSupport::Memoizable

Method deprecated or moved

This method is deprecated or moved on the latest stable version. The last existing version (v3.2.13) is shown here.

memoize(*symbols) public

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December 12, 2011
2 thanks

Need to extend class when using this

I had to dig around to find this out - if you want to use memoize somewhere, like an ActiveRecord model, you need to add

extend ActiveSupport::Memoizable

to the class. This doesn’t seem to be explained anywhere (the only docs are 3 year old blog posts anyway).

April 27, 2012 - (>= v3.2.1)
1 thank

Example from Code School

module Tweets

 class ShowPresenter
   extend ActiveSupport::Memoizable

   def initialize(tweet)
     @tweet = tweet

   def username

   def status

   def favorites_count

   memoize :username, :status, :favorites_count



July 9, 2012
0 thanks

this has been deprecated; replace with Memoist

In Rails 3.2, memoize has been deprecated. In edge Rails, it has been removed.

The commit when it was deprecated:

A Stack Overflow question about this change:

I personally disagree with the removal of memoize, and don’t recommend using the `||=` pattern Rails now suggests. The exception is if your entire program only memoizes something once or twice, so it’s not worth including a gem for.

The easiest way to keep using memoize is to use the Memoist gem ( ,, which is a simple extraction of ActiveSupport::Memoizable into its own gem.

November 10, 2015
0 thanks

instead of memoize

See this for deprecated


def something
  return @_var if defined? @_var
  # more code