3 ms·

This is simply not my experience with exceptions. Exceptions are frequently thrown and almost never need to be caught, and the result is easy to reason about.

This is simply not my experience with exceptions. Exceptions are frequently thrown and almost never need to be caught, and the result is easy to reason about. My main use case for exceptions is in server code with transactional semantics. Exceptions are a signal to roll everything back. That means only things that need rolling back need to pay much attention to exceptions, which is usually the top level in jobs, and whatever the transaction idiom is in the common library. There is very little call to handle exceptions in any other case. GC languages make safe rollback from exceptions much easier. C++ in particular with exceptions enabled has horrible composition effects with other features, like copy constructors and assignment operators, because exceptions can start cropping up unavoidably in operations where it's very inconvenient to safely maintain invariants during rollback. Mutable state is your enemy. If you don't have a transaction abstraction for your state mutation, then your life will be much more interesting. The answer isn't to give up on exceptions, though, because the irreducible complexity isn't due to exceptions; it's due to maintaining invariants after an error state has been detected. That remains the case whether you're using exceptions, error codes, Result or Either monadic types, or whatever.

woah 8y ago
Sounds very specific to server code
- minipci1321 8y ago
  Not sure which type of "server" you meant when you said that, is that in the narrow sense of database server? Behaviors similar to the above are not that infrequent, are expected from many other servers-in-wide-sense: media decoder would drop all decoding in progress and try to resynch to the next access unit, a communication front-end device would reset parts of itself and start re-acquiring channels (such exception-like reaction is even specified in some comm standards). Network processor would drop the packet and "fast-forward" to the next. Etc. You could argue that this still looks like a server behavior loosely defined (and I agree), but a) this makes application field for exceptions large enough IMO, and especially b) how differently could one implement all that with other mechanisms (like return codes), and for what benefits?
- jcelerier 8y ago
  > This is simply not my experience with exceptions. Exceptions are frequently thrown and almost never need to be caught, and the result is easy to reason about. I write GUI apps and that is also how I use exceptions - and it works just fine. If you have an exception, the only rational thing to do most of the time is to let it bubble up to the top of the event loop show a warning to the end user or cleanly quit the program while making a backup of the work somewhere else.

woah 8y ago

Sounds very specific to server code

minipci1321 8y ago
Not sure which type of "server" you meant when you said that, is that in the narrow sense of database server? Behaviors similar to the above are not that infrequent, are expected from many other servers-in-wide-sense: media decoder would drop all decoding in progress and try to resynch to the next access unit, a communication front-end device would reset parts of itself and start re-acquiring channels (such exception-like reaction is even specified in some comm standards). Network processor would drop the packet and "fast-forward" to the next. Etc. You could argue that this still looks like a server behavior loosely defined (and I agree), but a) this makes application field for exceptions large enough IMO, and especially b) how differently could one implement all that with other mechanisms (like return codes), and for what benefits?
jcelerier 8y ago
> This is simply not my experience with exceptions. Exceptions are frequently thrown and almost never need to be caught, and the result is easy to reason about. I write GUI apps and that is also how I use exceptions - and it works just fine. If you have an exception, the only rational thing to do most of the time is to let it bubble up to the top of the event loop show a warning to the end user or cleanly quit the program while making a backup of the work somewhere else.