this post was submitted on 13 Sep 2024
60 points (86.6% liked)
Programming
17670 readers
281 users here now
Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!
Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.
Hope you enjoy the instance!
Rules
Rules
- Follow the programming.dev instance rules
- Keep content related to programming in some way
- If you're posting long videos try to add in some form of tldr for those who don't want to watch videos
Wormhole
Follow the wormhole through a path of communities [email protected]
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
I think I disagree with everything here.
Well, they're "easier" in the same way that dynamic typing is easier. It's obviously less work initially just to say "screw it; any error gets caught in
main()
". But that's short term easiness. In the long term its much more painful because:(It actually gets worse than that but I can't think of a good example.)
Well... I'm guessing your codebase is a lot smaller than the other one for a start, and you're comparing with Go which is kind of worst case... But anyway this kind of proves my point! You only actually have proper error handling in 140 places - apparently mostly in tests. In other words you just throw all exceptions to
main()
.Kind of a fair point I guess. I dunno how you can reasonably stack overflows without exceptions. But guess what - Rust does have
panic!()
for that, and you can catch panics. I'd say that's one of the few reasonable cases to usecatch_unwind
.Hahahahahaha. I dunno if a bare stack trace with
NullPointerException
counts as a "better error message". Ridiculous.Sure maybe in error handling microbenchmarks, or particularly extreme examples. In real world code it clearly makes little difference. Certainly not enough to choose an inferior error handling system.
I would say one real reason to prefer exceptions over
Result<>
s is they are a fair bit easier to debug because you can just break on throw. That's tricky withResult<>
because creating aErr
is not necessarily an error. At least I have not found a way to "break onErr
". You can break onunwrap()
but that is usually after the stack has been unwound quite a bit and you lose all context.It can be pretty convenient to throw an error and be done with it. I think for some languages like Python, that is pretty much a prefered way to deal with things.
But the entire point of Rust and Result is as you say, to handle the places were things go wrong. To force you to make a choice of what should happen in the error path. It both forces you to see problems you may not be aware of, and handle issues in ways that may not stop the entire execution of your function. And after handling the Result in those cases, you know that beyond that point you are always in a good state. Like most things in Rust, that may involve making decisions about using Result and Option in your structs/functions, and designing your program in ways that force correct use... but that a now problem instead of a later problem when it comes up during runtime.
Checked exceptions also force you to handle it and take way less boilerplate.
But nothing is forcing you to check exeptions in most languages, right?
While not checking for exceptions and .unwrap() are pretty much the same, the first one is something you get by not doing anything extra while the latter is entirely a choice that has to be made. I think that is what makes the difference, and in similar ways why for example nullable enabled project in C# is desired over one that is not. You HAVE to check for null, or you can CHOOSE to assume it is not by trying to use the value directly. To me it makes a difference that we can accidentally forget about a possible exception or if we can choose to ignore it. Because problems dealt with early at compile time, are generally better than those that happen at runtime.
I see your concern, but in practice that's not what happens in languages like Java and Python with exceptions. Not checking for exceptions is a choice because everyone knows you need to check in your top-level functions. Forgetting to catch is a problem that only hits newbies.
There's also a massive tradeoff for when the error condition actually occurs. If an exception does get thrown and caught, that is comparatively slowwww.
The author pointed out how exceptions are often faster than checking every value. If your functions throws an error often enough that Exception handling noticeably slow down your program, surely you got to take a second look at what you're doing.
It depends what kind of errors you're talking about. Suppose you're implementing retries in a network protocol. You can get errors pretty regularly, and the error handling will be a nontrivial amount of your runtime.