Hands-On Reactive Programming with Python

Disposal should not throw exceptions

Disposal functions should not throw an exception, for the same reason that subscriptions should not throw exceptions: Since disposal may happen at any time during runtime, if a disposal function throws an exception, then the whole program stops. Unfortunately, unlike subscriptions, it is not possible to notify an error during disposal; the observer is already unsubscribed when the disposal function is called, and the disposal function does not return a value. So, the error can be silently handled in these cases, preferably logged to avoid losing it.