On 9 November 2017 at 07:46, Antoine Pitrou <anto...@python.org> wrote:
>
> Le 08/11/2017 à 22:43, Nick Coghlan a écrit :
>>
>> However, between them, the following two guidelines should provide
>> pretty good deprecation warning coverage for the world's Python code:
>>
>> 1. If it's in __main__, it will emit deprecation warnings at runtime
>> 2. If it's not in __main__, it should have a test suite
>
> Nick, have you actually read the discussion and the complaints people
> had with the current situation? Most of them *don't* specifically talk
> about __main__ scripts.
I have, and I've also re-read the discussions regarding why the
default got changed in the first place.
Behaviour up until 2.6 & 3.1:
once::DeprecationWarning
Behaviour since 2.7 & 3.2:
ignore::DeprecationWarning
With test runners overriding the default filters to set it back to
"once::DeprecationWarning".
The rationale for that change was so that end users of applications
that merely happened to be written in Python wouldn't see deprecation
warnings when Linux distros (or the end user) updated to a new Python
version. It had the downside that you had to remember to opt-in to
deprecation warnings in order to see them, which is a problem if you
mostly use Python for ad hoc personal scripting.
Proposed behaviour for Python 3.7+:
once::DeprecationWarning:__main__
ignore::DeprecationWarning
With test runners still overriding the default filters to set them
back to "once::DeprecationWarning".
This is a partial reversion back to the pre-2.7 behaviour, focused
specifically on interactive use and ad hoc personal scripting. For ad
hoc *distributed* scripting, the changed default encourages upgrading
from single-file scripts to the zipapp model, and then minimising the
amount of code that runs directly in __main__.py.
I expect this will be a sufficient change to solve the specific
problem I'm personally concerned by, so I'm no longer inclined to
argue for anything more complicated. Other folks may have other
concerns that this tweak to the default filters doesn't address - they
can continue to build their case for more complex options using this
as the new baseline behaviour.
Cheers,
Nick.
--
Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia
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