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Deprecation warning #20046

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Merged
merged 1 commit into from
May 10, 2021
Merged

Deprecation warning #20046

merged 1 commit into from
May 10, 2021

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brunobeltran
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@brunobeltran brunobeltran commented Apr 22, 2021 •
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PR Summary

We are currently unable to unintrusively deprecate class-level attributes (because we subclass UserWarning and not DeprecationWarning). Based on a previous dev call, we decided the solution was to "do it anyway". This led to a couple of issues, e.g. #19080 and #19839 and #19850.

The history of the decision to not subclass DeprecationWarning has to do with a decision from core Python in the 2.x days to not show DeprecationWarnings to users. However, there is now a more sophisticated filter in place (see https://www.python.org/dev/peps/pep-0565/).

Users that want to see MatplotlibDeprecationWarning in their CI will now have to export PYTHONWARNING=d, launch python with -Wa, or use warning filters to enable DeprecationWarnings (or MatplotlibDeprecationWarning specifically, depending on their needs).

PR Checklist

  • Has pytest style unit tests (and pytest passes).
  • Is Flake 8 compliant (run flake8 on changed files to check).
  • New features are documented, with examples if plot related.
  • Documentation is sphinx and numpydoc compliant (the docs should build without error).
  • Conforms to Matplotlib style conventions (install flake8-docstrings and run flake8 --docstring-convention=all).
  • New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
  • API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).

@anntzer
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anntzer commented Apr 22, 2021 •
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https://docs.python.org/3/library/exceptions.html#DeprecationWarning or https://docs.python.org/3/library/exceptions.html#FutureWarning? (see also https://www.python.org/dev/peps/pep-0565/#additional-use-case-for-futurewarning)

@brunobeltran brunobeltran marked this pull request as draft April 22, 2021 19:46
@QuLogic QuLogic added the status: needs comment/discussion needs consensus on next step label Apr 22, 2021
@brunobeltran brunobeltran marked this pull request as ready for review April 22, 2021 21:05
@brunobeltran
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CI failures seem unrelated.

jklymak
jklymak approved these changes Apr 23, 2021
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Reading at @anntzer link I still think this is the right deprecation here

@timhoffm
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timhoffm commented Apr 28, 2021 •
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Behavior for showing DeprecationWarnings according to https://www.python.org/dev/peps/pep-0565/:

Warning shows, when using deprecated functions

  • in interactive prompts, including notebooks
  • in scripts
  • in pytest runs

Warnings will continue to be silenced by default for packaged code distributed as part of an importable module.

I failed to construct such a case 👀

This still warns:

myscript.py  -- calls -->  mylib.plot() -- calls --> a deprecated Matplotlib function

where mylib is next to myscript. Maybe this is only suppressed if mylib is in site-packages?

Anyway given the above warning cases, I think it's safe enough to switch to DeprecationWarning.

@timhoffm timhoffm added this to the v3.5.0 milestone Apr 28, 2021
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Does this need an API change note?

@jklymak
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jklymak commented May 3, 2021

Definitely needs an API note!

@jklymak jklymak marked this pull request as draft May 3, 2021 14:31
@brunobeltran brunobeltran force-pushed the deprecation-warning branch from ed3d631 to 8c9af69 Compare May 6, 2021 18:07
@brunobeltran brunobeltran marked this pull request as ready for review May 6, 2021 18:12
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Squashed and added an API note.

Unsure where to dump all the information for most readability? Maybe a blog post on best practices for dealing with warnings for users/CI/library authors and would be more effective than putting some of this information in the docs?

@brunobeltran brunobeltran added status: needs merge and removed status: needs comment/discussion needs consensus on next step labels May 7, 2021
@jklymak jklymak merged commit 674d670 into matplotlib:master May 10, 2021
archlinux-github pushed a commit to archlinux/svntogit-community that referenced this pull request Aug 7, 2021
upgpkg: python-nbval 0.9.6-2; adopt the package, add missing dependen…
7c50f59 
…cy and fix check()

What a mess in tests LOL!

Related tickets:

[1] computationalmodelling/nbval#162
[2] computationalmodelling/nbval#167
[3] ipython/ipython#12817
[4] ipython/ipython#12889
[5] ipython/ipykernel#591
[6] matplotlib/matplotlib#20046

git-svn-id: file:///srv/repos/svn-community/svn@994636 9fca08f4-af9d-4005-b8df-a31f2cc04f65
archlinux-github pushed a commit to archlinux/svntogit-community that referenced this pull request Aug 7, 2021
upgpkg: python-nbval 0.9.6-2; adopt the package, add missing dependen…
5bb37c6 
…cy and fix check()

What a mess in tests LOL!

Related tickets:

[1] computationalmodelling/nbval#162
[2] computationalmodelling/nbval#167
[3] ipython/ipython#12817
[4] ipython/ipython#12889
[5] ipython/ipykernel#591
[6] matplotlib/matplotlib#20046


git-svn-id: file:///srv/repos/svn-community/svn@994636 9fca08f4-af9d-4005-b8df-a31f2cc04f65
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@jklymak jklymak jklymak approved these changes

@timhoffm timhoffm timhoffm approved these changes

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@brunobeltran @anntzer @timhoffm @jklymak @QuLogic