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Brilliant exception handling I found in an app i had to work on (media.kbin.social)

submitted 1 year ago by [email protected] to c/[email protected]

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Brilliant exception handling I found in an app i had to work on

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[–] [email protected] 2 points 1 year ago (1 children)

Actually, exception rethrowing is a real thing - at least in Java. You may not always want to handle the exception at the absolute lowest level, so sometimes you will instead "bubble" the exception up the callstack. This in turn can help with centralizing exception handling, separation of concerns, and making your application more modular.

It seems counter-intuitive but it's actually legit, again at least in Java. lol

[–] [email protected] 1 points 1 year ago (1 children)

Rethrowing caught exception in C# is just throw;, not throw ex;. This will delete old stack trace, which is very punishable if someone debugs your code later and you're still around.

[–] [email protected] 0 points 1 year ago (1 children)

I am a somewhat new C# developer (2 years). Could you explain more about this?

[–] [email protected] 1 points 1 year ago

throw ex; treats ex as a new exception, so, it starts a new stack trace for it from itself and deletes stack trace that was saved in ex.StackTrace. On the other hand, throw; takes already present exception in the scope and throws it without modifying the stack trace, preserving the original method that threw ex in the stack trace.

I feel like I wrote the same thing twice. I'm a bit bad with explaining stuff, feel free to ask more specific questions if you still don't understand the difference.

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago)

Seen this so many times, i weep for humanity

[–] [email protected] 1 points 1 year ago

while (true) {
    start();
}

[–] [email protected] 1 points 1 year ago (4 children)

Lol what’s wrong with this if the parent function catches it

[–] [email protected] 1 points 1 year ago

The catch is useless if it's just throwing the exception anyway

[–] [email protected] 1 points 1 year ago (1 children)

If this is C# (and it looks like it is), this leads to you losing the original stack trace up until this point.

The correct way to do this in C# is to just throw; after you're done with whatever you wanted to do in the catch.

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

wait what ?

So you are saying that the following code will keep throwing e but if I used throw e; it would basically be the same except for the stack trace that would be missing the important root cause ?!

try {
} catch (WhateverException e) {
    // stuff, or nothing, or whatever
    throw; 
}

[–] [email protected] 1 points 1 year ago

Exactly. Aside from deleting your already built stack trace, as a bonus you'll get another stack trace building call, enjoy wasted CPU cycles.

[–] [email protected] 1 points 1 year ago

You don't catch it if that's the case

[–] [email protected] 1 points 1 year ago

You could just not catch it and it'll get thrown up the stack anyway.

[–] [email protected] 0 points 1 year ago (1 children)

This can't compile, can it? Only a madman commits code which doesn't compile.

[–] [email protected] 1 points 1 year ago

Why wouldn't it? It's syntactically valid C#, with the added bonus of destroying the stack trace