On Tuesday, 3 February 2015 at 05:53:30 UTC, Jeremy DeHaan wrote:
Yes, they are not guaranteed to run, but isn't that only during run time? They are going to be called at the application exit to ensure everything is cleaned up.
If the application exits somewhat cleanly (through return from main or even a thrown exception in D), it will run, though I'm not sure if that's guaranteed or just an implementation convenience.
However, if the application exits differently, they won't necessarily be run. For example, a Unix signal terminating the process skips all the D cleanup tasks.
Often, this doesn't matter because the operating system will clean up a lot of resources anyway. But if you are using something like shared memory with another process, or expect a file to be written to in a destructor, you'll find those things never happen.
I had this problem once in simpledisplay.d. When it died by ctrl+c, the unix SIGINT was sent, and that skipped the destructors for shared images. As a result, the system eventually ran out of shared handles and most GUI programs wouldn't start up anymore until I cleaned it up some other way.
