While an exception might be marginally better than undefined behavior, its actual occurrence can still leave your database in an inconsistent state or have other random detrimental effects. By the time you see the exception reported the damage has already been done (program flow interrupted unexpectedly). Due to the large amount of possible program states you would have to do an impossible amount of testing to make sure such surprises won't happen once the software gets into the hands of a user.
>an exception might be marginally better than undefined behavior
The difference isn't marginal, it's night-and-day. Undefined behaviour means the program can behave in unpredictable ways, either now, or at some other time. If you're lucky, your whole process explodes immediately, but that's not guaranteed. Undefined behaviour is the root of many a nightmarish hidden bug.
> its actual occurrence can still leave your database in an inconsistent state or have other random detrimental effects
Not if your exception-handling code is correct, surely?
I agree though that there are good arguments to be made against exceptions as they exist in many languages, particularly regarding how it interferes with control flow 'from a distance' as it were. I defer to the excellent Raymond Chen: https://devblogs.microsoft.com/oldnewthing/?p=36693
The interesting question is not what you do once a catastrophe has happened (program has reached invalid state) but how to avoid it in the first place. Exceptions are better than undefined behavior in coping with the former, but they still don't help you with the latter. The idea to “make invalid states unrepresentable” would give you an actual shot at this.
> Exceptions are better than undefined behavior in coping with the former, but they still don't help you with the latter
That's not right. Exceptions are thrown reliably and are always 'noisy'. Undefined behaviour may go completely unnoticed for a long time. Code that wrongly throws exceptions tends to get fixed.
I've seen undefined behaviour in code samples in respected technical books. The code happened to work fine when using the MSVC C++ compiler and x84/AMD64 targets, and will probably continue to do so.
> The idea to “make invalid states unrepresentable” would give you an actual shot at this.
That's a pretty good summary of what type-systems research is aiming for.
