New submission from Barry A. Warsaw: As described here:
http://www.wefearchange.org/2013/04/python-3-language-gotcha-and-short.html the following code will produce an UnboundLocalError when the exception is triggered: def bad(): e = None try: do_something() except KeyError as e: print('ke') except ValueError as e: print('ve') print(e) The reason is that the exception handling machinery del's `e` from the local namespace in order to break circular references caused by __traceback__. The ULE is pretty mysterious and certainly not helpful for figuring out what's going wrong (the blog post above describes how long it took me to find it ;). Can we do better? What if instead of del'ing the target, we set it to None? We wouldn't get a ULE but the fact that print(e) would print None might be just as mysterious. Any other ideas? (BTW, there's likely nothing to be done for Python < 3.4.) ---------- messages: 187313 nosy: barry priority: normal severity: normal status: open title: Unhelpful UnboundLocalError due to del'ing of exception target versions: Python 3.4 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue17792> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
