It is an arena-style allocator. At least, if someone asked me to explain what an arena allocator is/does, I would say essentially what they wrote -- likely wit

It is an arena-style allocator. At least, if someone asked me to explain what an arena allocator is/does, I would say essentially what they wrote -- likely without the "disappears automatically once all references disappear" part, which is IMHO just a clever nice-to-have.