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Re: [Qemu-devel] [PATCH v4 1/2] qapi: Open files with encoding='utf-8'
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH v4 1/2] qapi: Open files with encoding='utf-8' |
Date: |
Tue, 19 Jun 2018 13:52:56 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Eduardo Habkost <address@hidden> writes:
> On Tue, Jun 19, 2018 at 08:28:08AM +0200, Markus Armbruster wrote:
>> Eduardo Habkost <address@hidden> writes:
>>
>> > On Mon, Jun 18, 2018 at 07:59:57PM +0200, Markus Armbruster wrote:
>> >> Python 2 happily reads UTF-8 files in text mode, but Python 3 requires
>> >> either UTF-8 locale or an explicit encoding passed to open(). Commit
>> >> d4e5ec877ca fixed this by setting the en_US.UTF-8 locale. Falls apart
>> >> when the locale isn't be available.
>> >>
>> >> Matthias Maier and Arfrever Frehtes Taifersar Arahesis proposed to use
>> >> binary mode instead, with manual conversion from bytes to str. Works,
>> >> but opening with an explicit encoding is simpler, so do that.
>> >>
>> >> Since Python 2's open() doesn't support the encoding parameter, we
>> >> need to suppress it with a version check.
>> >>
>> >> Reported-by: Arfrever Frehtes Taifersar Arahesis <address@hidden>
>> >> Reported-by: Matthias Maier <address@hidden>
>> >> Signed-off-by: Markus Armbruster <address@hidden>
>> >> ---
>> >> scripts/qapi/common.py | 17 ++++++++++++++---
>> >> 1 file changed, 14 insertions(+), 3 deletions(-)
>> >>
>> >> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
>> >> index 2462fc0291..832f11438a 100644
>> >> --- a/scripts/qapi/common.py
>> >> +++ b/scripts/qapi/common.py
>> >> @@ -16,6 +16,7 @@ import errno
>> >> import os
>> >> import re
>> >> import string
>> >> +import sys
>> >> from collections import OrderedDict
>> >>
>> >> builtin_types = {
>> >> @@ -340,7 +341,10 @@ class QAPISchemaParser(object):
>> >> return None
>> >>
>> >> try:
>> >> - fobj = open(incl_fname, 'r')
>> >> + if sys.version_info[0] >= 3:
>> >> + fobj = open(incl_fname, 'r', encoding='utf-8')
>> >> + else:
>> >> + fobj = open(incl_fname, 'r')
>> >
>> > I dislike the Python version check, but getting rid of it would
>> > require rewriting the QAPI modules to not use the Python 2 str
>> > type (that has different semantics from Python 3 str type).
>>
>> The version check is ugly, but it has a property I rather like: when we
>> drop support for Python 2, the conditional becomes True, and partial
>> evaluation results in the Python 3 code we actually want.
>>
>> > The python-future package would help us write code for a single
>> > file/string API instead of two different APIs, but it's not a
>> > QEMU build dependency (yet?), so this patch is good enough for
>> > now.
>>
>> Please do not invest more than absolutely necessary in Python 2 support.
>> All such investment will turn into technical debt in less than two
>> years. If you must invest, pick a solution that will result in less
>> technical debt. We can accept local ugliness for that.
>>
>> In my personal opinion, dumb ideas like supporting Python 2 this close
>> to its EOL ought to look ugly.
>
> That's the whole point: python-future allows us to not worry
> about Python 2 support in the code anymore because it exposes the
> Python 3 string API (and others) even if we're running Python 2.
>
> After we stop supporting Python 2, we can simply delete the "from
> __future__ import .*" and "from builtins import .*" lines.
You're right, __future__ is one of the least annoying ways to keep
Python 2 working. But is the improvement over my stupid, ugly solution
worth your while? You decide.
> Anyway, I will send a RFC series demonstrating that, and then we
> can discuss if it's worth it. My main worry is not the extra
> imports in Python code, but the introduction of a new build
> dependency only for a few (one?) releases.
The sane extra dependency to add would be Python 3. Not worth arguing
again; time's on my side ;)
>> > Reviewed-by: Eduardo Habkost <address@hidden>
>> > Acked-by: Eduardo Habkost <address@hidden>
>>
>> Uh, what does "Acked-by" add over "Reviewed-by"?
>
> It was supposed to indicate that I agree it can be merged through
> other maintainers. But it looks like this is not part of the
> original definition of "Acked-by"?
I'll drop the Acked-by then.
Re: [Qemu-devel] [PATCH v4 1/2] qapi: Open files with encoding='utf-8', Eric Blake, 2018/06/19