Riccardo Polignieri <ric....@libero.it> added the comment:
> `locale.getlocale()` is now returning strange results
Not really "strange results" - fact is, now "getlocale()" returns the locale
name *as if* it were already set from the beginnning (because it is, at least
in part).
Before:
>>> import locale # Python 3.7, new shell
>>> locale.getlocale()
(None, None)
>>> locale.setlocale(locale.LC_ALL, '') # say Hi from Italy
'Italian_Italy.1252'
>>> locale.getlocale()
('Italian_Italy', '1252')
now:
>>> import locale # Python 3.8, new shell
>>> locale.getlocale()
('Italian_Italy', '1252')
As for why returned locale names are "a little different" in Windows, I found
no better explanation that Eryk Sun's essays in
https://bugs.python.org/issue37945. Long story short, it's not even a bug
anymore... it's a hot mess and it won't be solved anytime soon.
But it's not the problem at hand, here. Returned locale names have not changed
between 3.7 and 3.8.
What *is* changed, though, is that now Python on Windows appears to set the
locale, implicitly, right from the start.
Except - maybe it does not, really:
>>> import locale # Python 3.8, new shell
>>> locale.getlocale()
('Italian_Italy', '1252')
>>> locale.localeconv()
{'int_curr_symbol': '', 'currency_symbol': '', 'mon_decimal_point': '',
'mon_thousands_sep': '', 'mon_grouping': [], 'positive_sign': '',
'negative_sign': '', 'int_frac_digits': 127, 'frac_digits': 127,
'p_cs_precedes': 127, 'p_sep_by_space': 127, 'n_cs_precedes': 127,
'n_sep_by_space': 127, 'p_sign_posn': 127, 'n_sign_posn': 127, 'decimal_point':
'.', 'thousands_sep': '', 'grouping': []}
As you can see, we have an Italian locale only in the name: the conventions are
still those of the default C locale.
If we explicitly set the locale, on the other hand...
>>> locale.setlocale(locale.LC_ALL, '')
'Italian_Italy.1252'
>>> locale.localeconv()
{'int_curr_symbol': 'EUR', 'currency_symbol': '€', ... ... }
... now we enjoy a real Italian locale - pizza, pasta, gelato and all.
What happened?
Unfortunately, this change of behaviour is NOT documented, except for a passing
note here: https://docs.python.org/3/whatsnew/changelog.html#id144. It's buried
*very* deep:
"""
bpo-34485: On Windows, the LC_CTYPE is now set to the user preferred locale at
startup. Previously, the LC_CTYPE locale was “C” at startup, but changed when
calling setlocale(LC_CTYPE, “”) or setlocale(LC_ALL, “”).
"""
This explains... something. Python now pre-sets *only* the LC_CTYPE category,
and that's why the other conventions remain unchanged.
Unfortunately, setting *that* one category changes the result yielded by
locale.getlocale(). But this is not a bug either, because it's the same
behaviour you would have in Python 3.7:
>>> locale.setlocale(locale.LC_CTYPE, '') # Python 3.7
'Italian_Italy.1252'
>>> locale.getlocale()
('Italian_Italy', '1252')
...and that's because locale.getlocale() with no arguments default, wait for
it, to getlocale(category=LC_CTYPE), as documented!
So, why Python 3.8 now pre-sets LC_CTYPE on Windows? Apparently, bpo-34485 is
part of the ongoing shakespearian feud between Victor Stinner and the Python
locale code. If you squint hard enough, you will see the answer here:
https://vstinner.github.io/locale-bugfixes-python3.html but at this point, I
don't know if anyone still keeps the score.
To sum up:
- there's nothing new about locale names - still the same mess;
- if locale names as returned by locale.getlocale() bother you, you should
follow Victor's advice here: https://bugs.python.org/issue37945#msg361806. Use
locale.setlocale(category, None) instead;
- if you relied on getlocale() with no arguments to test your locale, assuming
that either a locale is unset or it is "fully set", then you should stop now. A
locale can also be "partially set", and in fact it's just what happens now on
Windows by default. You should test for a specific category instead;
- changing the way the locale is set by default on Windows can be... rather
surprising and can lead to misunderstandings. I would certainly add a note in
the locale documentation to explain this new behaviour.
----------
nosy: +ricpol
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<https://bugs.python.org/issue38805>
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