gh-76007: Deprecate __version__ attribute in decimal

[StanFromIreland]

Per discussion in the issue, provide a SPEC_VERSION constant instead. CC @merwok @smontanaro

• Issue: Misleading __version__ attribute of modules in standard library #76007

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📚 Documentation preview 📚: https://cpython-previews--140302.org.readthedocs.build/

[vstinner]

cc @skirpichev @picnixz

[merwok]

(Please edit the commit message when merging so that we’re not tagged forever by pushes in clones! thanks 🙂)

[StanFromIreland]

(Please edit the commit message when merging so that we’re not tagged forever by pushes in clones! thanks 🙂)

Éric, all of my commits up to that point had the commit message "Commit"? I tagged you in the PR description, I don't think that should be a burden for longer than this PR is open? There is an "unsubscribe" button in the right sidebar.

[skirpichev]

Looks good, modulo one nitpick about decimal.rst.

I'm not sure also about naming for the constant. But lets see what other people think.

[skirpichev]

Hmm, I think that this should be moved up before "The constants in this section are only relevant for the C module." sentence of the first paragraph. Which should be also rephrased, i.e. "Following constants in <...>". Clearly, spec version is relevant for both modules.

BTW, I'm not sure about naming. Maybe more verbose "DECIMAL_SPEC_VERSION"?

[StanFromIreland]

BTW, I'm not sure about naming. Maybe more verbose "DECIMAL_SPEC_VERSION"?

I have a similar sentiment, I simply used this since it was in the discussion.

[skirpichev]

all of my commits up to that point had the commit message "Commit"? I tagged you in the PR description

It seems core devs sometimes use PR descriptions for commit messages. So, it's rather a reminder for one, who will merge this pr.

[hugovk]

I'm not sure also about naming for the constant. But lets see what other people think.

decimal.SPEC_VERSION is fine by me. Skip also suggested it at #76007 (comment).

[vstinner]

Merged, thank you.

[vstinner]

Oh, importing decimal does now emit a DeprecationWarning:

$ ./python -Werror -c "import decimal"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import decimal
  File "/home/vstinner/python/main/Lib/decimal.py", line 103, in <module>
    from _decimal import __version__  # noqa: F401
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
DeprecationWarning: '__version__' is deprecated and slated for removal in Python 3.20

[vstinner]

Oh, ignore my previous comment, I forgot to run make when testing an old PR :-)