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

  • @ipkpjersi
    7•1 year ago

    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

    • @TwilightKiddy@programming.dev
      3•1 year ago

      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.

      • @ipkpjersi
        1•1 year ago

        Oh, that makes more sense, just throw; in Java would be a syntax error lol

        • @TwilightKiddy@programming.dev
          1•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.

    • @chillhelm@lemmy.world
      3•1 year ago

      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.

    • @grimmi@feddit.de
      2•1 year ago

      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.

      • @jyte@lemmy.world
        2•1 year ago

        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; 
}
        • @TwilightKiddy@programming.dev
          1•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.

    • @Xanvial
      1•1 year ago

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