You are looking for the bug fix http://bugs.python.org/issue4180:
"warnings.simplefilter("always") does not make warnings always show up"
Python 2.7 has a bug, Python 3.4.3+ behaves correctly.
It is surprising that Python 3.4.0 and Python 3.4.3 behaves
differently :-) (Ubuntu 14.04 uses Python 3.4.0..
Victor
2016-11-14 14:58 GMT+01:00 Christoph Groth
(I assume that this list is appropriate for this topic, but if it isn't, I will be grateful for being redirected to the appropriate place.)
It seems that warnings behave differently in Python 2 and Python 3. Consider the following script.
**************** def func(): warnings.warn("Blabla", RuntimeWarning)
warnings.simplefilter("ignore") func() warnings.simplefilter("always") func() ****************
When run with CPython 2.7, there is no output, when run with CPython 3.5, there is the following output:
**************** /tmp/test.py:4: RuntimeWarning: Blabla warnings.warn("Blabla", RuntimeWarning) ****************
Was there indeed a change of how warnings behave in Python 3? I searched, but couldn't find any documentation for this.
Understanding how warnings work is especially important when testing for them. This is how I stumbled across this, in case anyone is interested: https://gitlab.kwant-project.org/kwant/kwant/issues/1#note_2608
I also note that the current documentation still uses DeprecationWarning in the example of how to suppress a warning: https://docs.python.org/dev/library/warnings.html#temporarily-suppressing-wa.... Since DeprecationWarning is disabled by default in modern Python, perhaps a different warning would provide a better example? _______________________________________________ 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/victor.stinner%40gmail.co...