It's no secret that expiring caches is hard. But it's also tedious, error-prone, and it forces a lot of duplication as your sweeper code is tightly coupled to how your views work. And caching itself introduces complexity: by caching data, you're creating multiple ways to compute the same value. What if we could get rid of all this? James will show Primer, a Rails extension that means you'll never write another cache sweeper.