Programmer Humor @lemmy.ml Zadyra @kbin.social 1y ago

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

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31 comments

Lol what’s wrong with this if the parent function catches it
- 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.
  
  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; }
  
  Exactly. Aside from deleting your already built stack trace, as a bonus you'll get another stack trace building call, enjoy wasted CPU cycles.
- Depending on the language it either does nothing and just adds code bloat or (and this would be much worse) it will catch any exception that can be implicitly cast to type Exception and throw it as type Exception. So the next higher scope would not be able to catch e.g. a RuntimeException or w.e. to handle appropriately. It could only catch a regular Exception even if the original error was a more detailed type.
  
  It's C# so it's just rethrowing the original exception.
  
  It might also be messing with the stack trace though which can be a bit frustrating for future debugging. But that's only a vague recollection of something I read in the past so I could be wrong
  
  Throwing exceptions are very costly due to the stack trace, so building the stack trace twice will cause a big performance hit
  
  Correct me if I'm wrong, but this will actually cut the stack trace and then start another one from your try-catch block, which is an evil thing to do towards those who will actually read your stack traces. To preserve the stack trace you do throw;, not throw ex;, and I'm assuming IDE is underlining that statement exactly for this reason.
  
  Yes, hence why I mentioned it collects the stack trace twice.
  
  It's more than just more difficult for debugging
- You don't catch it if that's the case
- The catch is useless if it's just throwing the exception anyway
  
  The catch is mandatory...
- You could just not catch it and it'll get thrown up the stack anyway.
- Then the parent function would catch the original exception if it was never caught in the first place. All this does is bork the stacktrace.

31 comments