Let's discuss -Xdev implementation issue at https://bugs.python.org/issue32230
In short, -Xdev must add its warning at the end to respect BytesWarning, whereas it's not possible with -W option :-( Victor Le 6 déc. 2017 09:15, "Nick Coghlan" <ncogh...@gmail.com> a écrit : On 6 December 2017 at 14:50, Nick Coghlan <ncogh...@gmail.com> wrote: > On 6 December 2017 at 14:34, Nick Coghlan <ncogh...@gmail.com> wrote: >> That said, I go agree we could offer easier to use APIs to app >> developers that just want to hide warnings from their users, so I've >> filed https://bugs.python.org/issue32229 to propose a straightforward >> "warnings.hide_warnings()" API that encapsulates things like checking >> for a non-empty sys.warnoptions list. > > I've updated the "Limitations" section of the PEP to mention that > separate proposal: > https://github.com/python/peps/commit/6e93c8d2e6ad698834578d4077b92a 8fc84a70f5 Having rebased the PEP 565 patch atop the "-X dev" changes, I think that if we don't change some of the details of how `-X dev` is implemented, `warnings.hide_warnings` (or a comparable convenience API) is going to be a requirement to help app developers effectively manage their default warnings settings in 3.7+. The problem is that devmode doesn't currently behave the same way `-Wd` does when it comes to sys.warnoptions: $ ./python -Wd -c "import sys; print(sys.warnoptions); print(sys.flags.dev_mode)" ['d'] False $ ./python -X dev -c "import sys; print(sys.warnoptions); print(sys.flags.dev_mode)" [] True As currently implemented, the warnings module actually checks `sys.flags.dev_mode` directly during startup (or `sys._xoptions` in the case of the pure Python fallback), and populates the warnings filter differently depending on what it finds: $ ./python -c "import warnings; print('\n'.join(map(str, warnings.filters)))" ('default', None, <class 'DeprecationWarning'>, '__main__', 0) ('ignore', None, <class 'DeprecationWarning'>, None, 0) ('ignore', None, <class 'PendingDeprecationWarning'>, None, 0) ('ignore', None, <class 'ImportWarning'>, None, 0) ('ignore', None, <class 'BytesWarning'>, None, 0) ('ignore', None, <class 'ResourceWarning'>, None, 0) $ ./python -X dev -c "import warnings; print('\n'.join(map(str, warnings.filters)))" ('ignore', None, <class 'BytesWarning'>, None, 0) ('default', None, <class 'ResourceWarning'>, None, 0) ('default', None, <class 'Warning'>, None, 0) $ ./python -Wd -c "import warnings; print('\n'.join(map(str, warnings.filters)))" ('default', None, <class 'Warning'>, None, 0) ('default', None, <class 'DeprecationWarning'>, '__main__', 0) ('ignore', None, <class 'DeprecationWarning'>, None, 0) ('ignore', None, <class 'PendingDeprecationWarning'>, None, 0) ('ignore', None, <class 'ImportWarning'>, None, 0) ('ignore', None, <class 'BytesWarning'>, None, 0) ('ignore', None, <class 'ResourceWarning'>, None, 0) This means the app development snippet proposed in the PEP will no longer do the right thing, since it will ignore the dev mode flag: if not sys.warnoptions: # This still runs for `-X dev` warnings.simplefilter("ignore") My main suggested fix would be to adjust the way `-X dev` is implemented to include `sys.warnoptions.append('default')` (and remove the direct dev_mode query from the warnings module code). However, another possible way to go would be to make the correct Python 3.7+-only snippet look like this: import warnings warnings.hide_warnings() And have the forward-compatible snippet look like this: import warnings: if hasattr(warnings, "hide_warnings"): # Accounts for `-W`, `-X dev`, and any other implementation specific settings warnings.hide_warnings() else: # Only accounts for `-W` import sys if not sys.warnoptions: warnings.simplefilter("ignore") (We can also do both, of course) Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
