[issue22298] Lib/warnings.py _show_warning does not protect against being called with a file like object which is closed
Julius Lehmann-Richter added the comment: Hey Wolfgang, thank you for the clarification. I would never write such code of course, I stumbled across this with a third-party program. I understand your point of view and I actually agree. I would not have even opened this report if it had not been for that comment. If the error is still reproducable in the software I will open a bug with them instead and tell them to please fix it :P As far as I am concerned this is not a bug (any more) Cheers Julius -- ___ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue22298> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22298] Lib/warnings.py _show_warning does not protect against being called with a file like object which is closed
Julius Lehmann-Richter added the comment: Hey Wolfgang, thank you for looking into this old one again ;) The argument you are making does not answer the original bug report though as far as I can see. My initial problem was not the AttributeError about the missing write but a ValueError (I/O operation on closed file). Also this seems to have started a discussion about good programming practice between Terry and Antoine, my initial argument though was that, when you are catching an IOError for an invalid file, why not catch the ValueError for the closed file (since a closed file is surely not a valid target for a write operation). I would really like to be educated on this if I am missing something, why does the argument for not silencing errors and expecting good programming practice apply to the ValueError of a closed standard error which has not been set to None but not to an IOError of a passed in file object? Cheers Julius -- ___ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue22298> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22298] Lib/warnings.py _show_warning does not protect against being called with a file like object which is closed
New submission from Julius Lehmann-Richter: In Lib/warnings.py the _show_warning function catches IOError with the commented intention to ward against an invalid file: def _show_warning(message, category, filename, lineno, file=None, line=None): Hook to write a warning to a file; replace if you like. if file is None: file = sys.stderr try: file.write(formatwarning(message, category, filename, lineno, line)) except IOError: pass # the file (probably stderr) is invalid - this warning gets lost. If for some reason the file like object, and in the default case stderr, is closed, a calling program is faced with a ValueError, which is not being caught. It seems to me, and correct me if I am wrong, that a file object which has been closed is a case of an invalid file and that the warning subsystem should in that case behave in the same manner as in the case of the IOError. This behavior is the same for python 3.2 with the function renamed to showwarning and can be reproduced with for example from sys import stderr from warnings import warn stderr.close() try: warn(foo) except ValueError as e: print(e) -- components: Library (Lib) messages: 226058 nosy: Julius.Lehmann-Richter priority: normal severity: normal status: open title: Lib/warnings.py _show_warning does not protect against being called with a file like object which is closed type: behavior versions: Python 2.7, Python 3.2 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22298 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
