Introducing cached_attribute - cached values across object instances

We've been memoizing attributes manually for a long time, and since we're still on Rails 2.1, we haven't been able to use the nifty new features for memoization. I liked the way Rails 2.2 did it, though, and revisited it when we were investigating some perf issues on the site. Memoization is cool and all, but it didn't buy us anything when we had multiple instances of the same object on the same page, so that's where cached_attribute comes in. Cached_attribute is a plugin that stashes the result of an expensive calculation into a cache, indexed by the object's id. That way, multiple object instances will share the same cached value for the same attribute (on the same object). The readme has more information and an example, or you could just check out the code:

ruby script/plugin install git://github.com/avvo/cached_attribute.git

And as usual, the project is available on github.