[Python-Dev] PEP 538 (review round 2): Coercing the legacy C locale to a UTF-8 based locale

[Nick Coghlan]

On 24 May 2017 at 02:34, Nick Coghlan <ncoghlan at gmail.com> wrote:
> On 23 May 2017 at 18:38, INADA Naoki <songofacandy at gmail.com> wrote:
>> Would you add example demonstrates how coercing LANG helps people?
>
> I'm honestly not sure it does - I think it's an assumption I added to
> the PEP early on, and never actually tested. Looking at it more
> closely now, all of the interpreter level checks are specifically for
> LC_CTYPE, and experimenting with "LANG=C LC_CTYPE=C.UTF-8" indicates
> that coercing only LC_CTYPE is still enough to fix the GNU readline
> encoding compatibility problem covered in
> https://www.python.org/dev/peps/pep-0538/#considering-locale-coercion-independently-of-utf-8-mode
>
> So I'll take another pass through the implementation this weekend, and
> simplify it to only set LC_CTYPE regardless of whether it's using
> C.UTF-8, C.utf8, or UTF-8 as the target locale. Assuming that doesn't
> uncover any hidden problems with the idea, I'll then update the PEP to
> match.

I've now gone through this, and as far as I can tell, setting only
LC_CTYPE is sufficient to handle all the scenarios that the PEP aims
to address, and has fewer potential side effects than setting both
LC_CTYPE and LANG.

Accordingly, I've updated both the PEP and the implementation to only
set LC_CTYPE and leave LANG alone:

* PEP: https://github.com/python/peps/commit/12cecb05489e74a36a11c17e8d0b1e36e3768bda
* Implementation:
https://github.com/python/cpython/pull/659/commits/939ba0a77d4b52a04315c129f9db89b90c0532cd

Regards,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia