Throwing twice in the same method is probably a special case – I’ve not been able to create a stack trace where different lines in the same method follow each other. As the word says, a “stack trace” shows you the stack frames that an exception traversed. And there is only one stack frame per … Read more
Try it and see: def failure(): raise ValueError, “Real error” def apologize(): raise TypeError, “Apology error” try: failure() except ValueError: apologize() raise The result: Traceback (most recent call last): File “<pyshell#14>”, line 10, in <module> apologize() File “<pyshell#14>”, line 5, in apologize raise TypeError, “Apology error” TypeError: Apology error The reason: the “real” error from … Read more
From “Declarations” in the Swift book: Rethrowing Functions and Methods A function or method can be declared with the rethrows keyword to indicate that it throws an error only if one of its function parameters throws an error. These functions and methods are known as rethrowing functions and rethrowing methods. Rethrowing functions and methods must … Read more
In both cases, since you catch by reference, you are effectively altering the state of the original exception object (which you can think of as residing in a magical memory location which will stay valid during the subsequent unwinding — 0x98e7058 in the example below). However, In the first case, since you rethrow with throw; … Read more
The way to preserve the stack trace is through the use of the throw; This is valid as well try { // something that bombs here } catch (Exception ex) { throw; } throw ex; is basically like throwing an exception from that point, so the stack trace would only go to where you are … Read more