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| References | (4 earlier) <mailman.411.1426484388.21433.python-list@python.org> <55068cb0$0$12923$c3e8da3$5496439d@news.astraweb.com> <8761a1gxhq.fsf@jester.gateway.sonic.net> <CAEfz+TxKBdUrhxUT43Bq5Td=G9Nbu1ANHjF2Ou1tPfih8PNh6w@mail.gmail.com> <me7505$rnp$1@ger.gmane.org> |
|---|---|
| From | INADA Naoki <songofacandy@gmail.com> |
| Date | 2015-03-17 04:41 +0900 |
| Subject | Re: Python 2 to 3 conversion - embrace the pain |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.462.1426534899.21433.python-list@python.org> (permalink) |
On Tue, Mar 17, 2015 at 2:47 AM, Terry Reedy <tjreedy@udel.edu> wrote:
> On 3/16/2015 5:13 AM, INADA Naoki wrote:
>
>> Another experience is porting Flask application in my company from
>> Python 2 to Python 3.
>> It has 26k lines of code and 7.6k lines of tests.
>>
>> Since we don't need to support both of PY2 and PY3, we used 2to3.
>> 2to3 changes 740 lines.
>
>
> That is less than 3% of the lines. Were any changes incorrect? How many
> lines *not* flagged by 2to3 needed change?
All changes are OK. Flask (and Werkzeug) handles most part of pain.
Application using Flask uses unicode most everywhere on Python 2 already.
Few changes 2to3 can't handle is like this:
- reader = DictReader(open(file_path, 'r'), delimiter='\t')
+ reader = DictReader(open(file_path, 'r', encoding='utf-8'), delimiter='\t')
Since csv module in Python 2 doesn't support unicode, we had to parse
csv as bytestring.
And our server doesn't have utf-8 locale, we should specify encoding
explicitly on PY3.
There were few (less than 10, maybe) easy trouble like this.
>
>> I had to replace google-api-client with
>> requests+oauthlib since
>> it had not supported PY3 yet.
>
>
> Other than those needed for this change, which 2to3 could not anticipate or
> handle?
>
>> After that, we encountered few trouble with untested code. But Porting
>> effort is surprisingly small.
>> We're happy now with Python 3. We can write non-ascii string to log
>> without fear of UnicodeError.
>> We can use csv with unicode without hack.
>
>
> People who use ascii only or perhaps one encoding everywhere severely
> underestimate the benefit of unicode strings (and utf-8) everywhere.
I agree. We may lost log easily on Python 2. It makes investigating bug hard.
>>> import logging
>>> logging.error("%s %s", u'こんにちは', 'こんにちは')
Traceback (most recent call last):
...
File "/usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/lib/python2.7/logging/__init__.py",
line 335, in getMessage
msg = msg % self.args
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe3 in
position 0: ordinal not in range(128)
Logged from file <stdin>, line 1
And log including unicode is hard to read.
>>> logging.error("%s", [u'こんにちは'])
ERROR:root:[u'\u3053\u3093\u306b\u3061\u306f']
Python 3 makes our development faster and easier.
Since old Python programmers knows how to avoid pitfalls in Python 2,
writing Python 2 is not a pain.
But when teaching Python to PHP programmer, teaching tons of pitfalls is pain.
This is why I think new applications should start with Python 3.
>
>> Porting *modern* *application* code to *PY3 only* is easy, while
>> porting libraries on the edge of
>> bytes/unicode like google-api-client to PY2/3 is not easy.
>>
>> I think application developers should use *only* Python 3 from this year.
>> If we start moving, more library developers will be able to start
>> writing Python 3 only code from next year.
>
>
> --
> Terry Jan Reedy
>
> --
> https://mail.python.org/mailman/listinfo/python-list
--
INADA Naoki <songofacandy@gmail.com>
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Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-16 14:22 +1100
Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-15 22:07 -0700
Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-16 16:39 +1100
Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-15 23:17 -0700
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 19:00 +1100
Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-16 01:31 -0700
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 00:05 +1100
Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-17 00:29 +1100
Re: Python 2 to 3 conversion - embrace the pain Terry Reedy <tjreedy@udel.edu> - 2015-03-16 13:59 -0400
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 18:56 +1100
Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-16 01:25 -0700
Re: Python 2 to 3 conversion - embrace the pain INADA Naoki <songofacandy@gmail.com> - 2015-03-16 18:13 +0900
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 22:55 +1100
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 01:25 +1100
Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-16 15:36 -0700
Re: Python 2 to 3 conversion - embrace the pain Terry Reedy <tjreedy@udel.edu> - 2015-03-16 22:28 -0400
Re: Python 2 to 3 conversion - embrace the pain wxjmfauth@gmail.com - 2015-03-17 01:31 -0700
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 22:26 +1100
Re: Python 2 to 3 conversion - embrace the pain wxjmfauth@gmail.com - 2015-03-17 07:03 -0700
Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-17 15:35 +0100
Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-19 16:23 -0700
Re: Python 2 to 3 conversion - embrace the pain Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-03-19 22:03 -0400
Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-20 03:54 +0100
Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 11:20 -0600
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 07:36 +1100
Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 20:14 -0600
Re: Python 2 to 3 conversion - embrace the pain Cameron Simpson <cs@zip.com.au> - 2015-03-17 17:47 +1100
Re: Python 2 to 3 conversion - embrace the pain Terry Reedy <tjreedy@udel.edu> - 2015-03-16 13:47 -0400
Re: Python 2 to 3 conversion - embrace the pain Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-16 18:14 +0000
Re: Python 2 to 3 conversion - embrace the pain INADA Naoki <songofacandy@gmail.com> - 2015-03-17 04:41 +0900
Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-17 09:02 +1100
Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-17 04:04 +0100
Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 21:33 -0600
Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 19:36 +1100
Re: Python 2 to 3 conversion - embrace the pain Ben Finney <ben+python@benfinney.id.au> - 2015-03-17 14:42 +1100
Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-17 05:30 +0100
Re: Python 2 to 3 conversion - embrace the pain Cameron Simpson <cs@zip.com.au> - 2015-03-18 08:53 +1100
Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-17 14:49 +1100
Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-17 05:26 +0100
Re: Python 2 to 3 conversion - embrace the pain Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 04:36 +0000
Re: Python 2 to 3 conversion - embrace the pain Grant Edwards <invalid@invalid.invalid> - 2015-03-17 14:50 +0000
Re: Python 2 to 3 conversion - embrace the pain wxjmfauth@gmail.com - 2015-03-17 08:15 -0700
Re: Python 2 to 3 conversion - embrace the pain Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-03-17 18:36 -0400
Re: Python 2 to 3 conversion - embrace the pain Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 22:41 +0000
Re: Python 2 to 3 conversion - embrace the pain Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-03-18 08:04 -0400
Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-18 02:02 +0100
[OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 19:46 -0600
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 19:39 +1100
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-17 09:02 -0600
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-19 16:37 -0600
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain wxjmfauth@gmail.com - 2015-03-20 02:40 -0700
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-20 15:59 +0100
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-20 16:03 +0100
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-20 15:42 +0000
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-21 04:13 +1100
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain wxjmfauth@gmail.com - 2015-03-20 12:21 -0700
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-17 12:57 +1100
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-16 19:45 -0700
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 21:05 -0600
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 20:07 -0600
Re: Python 2 to 3 conversion - embrace the pain Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 02:21 +0000
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Ben Finney <ben+python@benfinney.id.au> - 2015-03-17 13:40 +1100
Package manager cooperation? (was Weaknesses of distro package managers) Rustom Mody <rustompmody@gmail.com> - 2015-03-16 20:09 -0700
Re: Package manager cooperation? (was Weaknesses of distro package managers) Michael Torrie <torriem@gmail.com> - 2015-03-16 21:32 -0600
Re: Package manager cooperation? (was Weaknesses of distro package managers) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 04:03 +0000
Re: Package manager cooperation? (was Weaknesses of distro package managers) Chris Angelico <rosuav@gmail.com> - 2015-03-17 15:18 +1100
Re: Package manager cooperation? (was Weaknesses of distro package managers) wxjmfauth@gmail.com - 2015-03-17 01:44 -0700
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 20:51 -0600
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 03:01 +0000
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Michael Torrie <torriem@gmail.com> - 2015-03-16 21:05 -0600
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Mario Figueiredo <marfig@gmail.com> - 2015-03-17 04:07 +0100
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 03:17 +0000
Re: [OT] Weaknesses of distro package managers - was Re: Python 2 to 3 conversion - embrace the pain Alexander <xr.lists@gmail.com> - 2015-03-17 16:44 +1300
Re: Python 2 to 3 conversion - embrace the pain Chris Angelico <rosuav@gmail.com> - 2015-03-16 19:51 +1100
Re: Python 2 to 3 conversion - embrace the pain Terry Reedy <tjreedy@udel.edu> - 2015-03-16 04:53 -0400
Re: Python 2 to 3 conversion - embrace the pain Paul Rubin <no.email@nospam.invalid> - 2015-03-16 02:27 -0700
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