locale.setlocale example incorrect

[pintman]

BPO	41032
Nosy	@Barathwaja, @pintman

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-06-19.09:26:58.820>
labels = ['3.8', 'type-feature', '3.7', 'docs']
title = 'locale.setlocale example incorrect'
updated_at = <Date 2020-08-17.11:31:56.409>
user = 'https://github.com/pintman'

bugs.python.org fields:

activity = <Date 2020-08-17.11:31:56.409>
actor = 'pintman'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2020-06-19.09:26:58.820>
creator = 'pintman'
dependencies = []
files = []
hgrepos = []
issue_num = 41032
keywords = []
message_count = 3.0
messages = ['371860', '375514', '375541']
nosy_count = 3.0
nosy_names = ['docs@python', 'Barathwaja', 'pintman']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue41032'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']

[pintman]

The example given results in an error.

https://docs.python.org/3.8/library/locale.html?highlight=locale

>> locale.setlocale(locale.LC_ALL, 'de_DE')

I could be improved with one of the following versions:

>> locale.setlocale(locale.LC_ALL, 'de_DE.UTF-8')
>> locale.setlocale(locale.LC_ALL, ('de_DE'), ('UTF-8'))

[Barathwaja]

Hi Marco,

Can I work on this?

[pintman]

I have only reported the bug and do not know exactly how to proceed. I don't think there's anything wrong with taking over the bug.

[slateny]

The example seems to fail on Ubuntu, but runs on Windows - there is a comment right above the line that says name might vary with platform. It does seem that locale.setlocale(locale.LC_ALL, 'de_DE.UTF-8') works on both platforms though, so maybe it can be changed to that

[StanFromIreland]

This is still not a universal fix and UTF-8 locale on windows are quite a new thing. There is no "universal" fix that will cover all platforms that I know of and the current comment that covers this is fine.

[encukou]

Depends on what locales are installed; on a minimal Ubuntu container not even 'de_DE.UTF-8' will work.
IMO it would be good to mention 'de_DE.UTF-8' in the docs, but also note that locale availability (and not just naming) might vary with platform.

[picnixz]

Adding an other example from #91343 (comment):

The example in the doc shows

>>> import locale
>>> loc = locale.getlocale()  # get current locale
# use German locale; name might vary with platform
>>> locale.setlocale(locale.LC_ALL, 'de_DE')
>>> locale.strcoll('f\xe4n', 'foo')  # compare a string containing an umlaut
>>> locale.setlocale(locale.LC_ALL, '')   # use user's preferred locale
>>> locale.setlocale(locale.LC_ALL, 'C')  # use default (C) locale
>>> locale.setlocale(locale.LC_ALL, loc)  # restore saved locale

However locale.getlocale() does not return the locale for all categories (locale.LC_ALL is even not allowed) but the locale for the LC_CTYPE category.

Therefore restoring it using locale.setlocale(locale.LC_ALL, loc) does not actually restore the initial settings, and may even fail on some platforms (on mine it does).

The correct example should have the first line of code replaced with

>>> loc = locale.setlocale(locale.LC_ALL)  # get current locale

Note: this issue was first reported in the pandas library at pandas-dev/pandas#46595