Is RAII recommended in Swift?

[rayx (Huan Xiong)]

@Joe_Groff

For writing in Swift, I would recommend that mandatory exit-time (and start-time, for that matter) operations be done explicitly in your main() or top-level rather than rely on any implicit mechanisms.

Do I understand correctly that doing clean-up in, say, SIGTERM handler is explicit and implicit mechanisms mainly refer to the code in deinit?

@Nobody1707

Don't try to use deinit for RAII was the general advice of the Swift team before non-copyable types were added as well as during the initial discussions of ownership in 2017. The core team clearly changed their minds since then, but if one hadn't been keeping up very closely it'd be easy to miss that they had.

Was it because the introduction of non-copyable type? But I think the exit-time clean up issue discussed in this thread applies to it too.

Take @spacecrafter3d's app as an example, a Connection instance may be destroyed when A) it's replaced by a new instance, and B) when the process exits. According to this thread, case B is unreliable (in this specific example, the websocket related network resource will be released by OS when the process terminates, so it's OK. But if it was app specific cleanup, such as saving data chagnes, it would be an issue). Since the root cause is due to the unstable environment on process exit, I don't think using non-copyable type can change it.