I just read that support for an identity map has just been merged into ActiveRecord. This has been a long time coming and I’m really happy it’s here. Huge thanks to Emilio Tagua for doing this.
In some of my projects an identity map would have saved a lot of ugliness. I’m going to start using this feature in small projects as soon as it’s released. Once it has proven itself to me it will become part of my app template for all my projects. (It’s turned off by default, which seems reasonable for now.)
Read more about it in the link above.