locale module example is wrong for some platforms · Issue #91343 · python/cpython

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