Remove recommendation in curses module documentation to initialize LC_ALL and encode strings

[manueljacob]

BPO	41091
Nosy	@manueljacob
PRs	bpo-41091: Remove recommendation in curses module documentation to initialize LC_ALL and encode strings #21159

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assignee = None
closed_at = None
created_at = <Date 2020-06-23.15:26:57.516>
labels = ['docs']
title = 'Remove recommendation in curses module documentation to initialize LC_ALL and encode strings'
updated_at = <Date 2020-06-25.22:25:01.188>
user = 'https://github.com/manueljacob'

bugs.python.org fields:

activity = <Date 2020-06-25.22:25:01.188>
actor = 'mjacob'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2020-06-23.15:26:57.516>
creator = 'mjacob'
dependencies = []
files = []
hgrepos = []
issue_num = 41091
keywords = ['patch']
message_count = 1.0
messages = ['372178']
nosy_count = 2.0
nosy_names = ['docs@python', 'mjacob']
pr_nums = ['21159']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue41091'
versions = []

[manueljacob]

The documentation for the curses module (https://docs.python.org/3.9/library/curses.html) has the following note:

Since version 5.4, the ncurses library decides how to interpret non-ASCII data using the nl_langinfo function. That means that you have to call locale.setlocale() in the application and encode Unicode strings using one of the system’s available encodings. This example uses the system’s default encoding:

import locale
locale.setlocale(locale.LC_ALL, '')
code = locale.getpreferredencoding()

Then use code as the encoding for str.encode() calls.

The recommendation to call locale.setlocale(locale.LC_ALL, '') is problematic as it initializes all locale categories to the user settings, which might be unintended and is not necessary for curses to work correctly. Initializing LC_CTYPE is sufficient for nl_langinfo() to return the correct encoding. Current versions of Python (*) initialize LC_CTYPE at interpreter startup. Therefore calling locale.setlocale() should not be necessary at all.

The curses module automatically encodes strings. Therefore the recommendation to manually encode strings is outdated.

(*) It seems to be the case since 177d921. Why was is not previously done on Python 2 and on Python 3 on Windows?

[iritkatriel]

Duplicate of #91156.