> Iterators, async functions and async iterators don't work well here because they have different semantics to standard functions. When you call them they return immediately with a generator object, coroutine function and async generator object respectively. So the decorator completes immediately as opposed to the entire lifecycle what it's wrapping.

> This is an unfortunate problem I've encountered many times, and it's often a problem for normal decorators too. But this has changed in 3.15, now the ContextDecorator will check the type of the function it's wrapping and ensure that the decorator covers the entire lifespan.

I very much like the idea of that change - but it also seems kind of dangerous, to do this with no "opt-in mechanism", as that quite subtly changes the behavior of existing usage sites.

This is a bit of a "spacebar heating" situation, because someone would have to intentionally use a decorator in the old, broken way, but if someone actually did that, things may unexpectedly break.