It's sad the difference between expiry and eviction isn't explored more fully. There are plenty of posts describing cache eviction strategies that barely touch on expiry issues, and a handful of posts about cache expiry that barely touch on eviction.

Regarding the decorators, there's a reason it's popular: it saves boilerplate. The good news is that it's python, so you can do something like this:

  from pyappcache import RedisCache

  @RedisCache
  def get_slow_thing_v3(thing_id):
      thing = get_slow_thing_from_a_database_layer()
      return thing

  def update_something_slow(thing_id, new_thing):
      get_slow_thing_v3.set_cache(thing_id, new_thing)
      set_thing_in_a_database_layer(new_thing)