Changing the “locale preferred encoding” in Python 3 in Windows

Question

I'm using Python 3 (recently switched from Python 2). My code usually runs on Linux but also sometimes (not often) on Windows. According to Python 3 documentation for open(), the default encoding for a text file is from locale.getpreferredencoding() if the encoding arg is not supplied. I want this default value to be utf-8 for a project of mine, no matter what OS it's running on (currently, it's always UTF-8 for Linux, but not for Windows). The project has many many calls to open() and I don't want to add encoding='utf-8' to all of them. Thus, I want to change the locale's preferred encoding in Windows, as Python 3 sees it.

I found a previous question "Changing the "locale preferred encoding"", which has an accepted answer, so I thought I was good to go. But unfortunately, neither of the suggested commands in that answer and its first comment work for me in Windows. Specifically, that accepted answer and its first comment suggest running chcp 65001 and set PYTHONIOENCODING=UTF-8, and I've tried both. Please see transcript below from my cmd window:

> py -i
Python 3.4.3 ...
>>> f = open('foo.txt', 'w')
>>> f.encoding
'cp1252'
>>> exit()

> chcp 65001
Active code page: 65001

> py -i
Python 3.4.3 ...
>>> f = open('foo.txt', 'w')
>>> f.encoding
'cp1252'
>>> exit()

> set PYTHONIOENCODING=UTF-8

> py -i
Python 3.4.3 ...
>>> f = open('foo.txt', 'w')
>>> f.encoding
'cp1252'
>>> exit()

Note that even after both suggested commands, my opened file's encoding is still cp1252 instead of the intended utf-8.

Answer 1

As of python3.5.1 this hack looks like this:

import _locale
_locale._getdefaultlocale = (lambda *args: ['en_US', 'utf8'])

All files opened thereafter will assume the default encoding to be utf8.