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Date:      Wed, 31 Aug 2011 21:02:50 +0400
From:      Ruslan Mahmatkhanov <cvs-src@yandex.ru>
To:        glarkin@FreeBSD.org
Cc:        FreeBSD Ports Mailing List <ports@freebsd.org>, miwi@FreeBSD.org
Subject:   Re: Python min version bumped from 2.4+ to 2.5+
Message-ID:  <4E5E693A.8060608@yandex.ru>
In-Reply-To: <4E5E52C4.4090308@FreeBSD.org>
References:  <4E5CE015.70803@FreeBSD.org>	<4E5CE7BB.8050808@yandex.ru>	<4E5CEC1E.5010209@FreeBSD.org>	<4E5CF2FF.5080302@yandex.ru> <4E5D42FC.6060600@FreeBSD.org> <4E5D4750.2010507@yandex.ru> <4E5E52C4.4090308@FreeBSD.org>

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Greg Larkin wrote on 31.08.2011 19:27:
>>>>>>> Hi Martin,
>>>>>>>
>>>>>>> I have a question about a commit you made in February 2011:
>>>>>>> http://www.freshports.org/commit.php?message_id=201102250750.p1P7ofDg016541@repoman.freebsd.org&files=yes
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Part of the commit changed:
>>>>>>>
>>>>>>> USE_PYTHON=    2.4+
>>>>>>>
>>>>>>> to
>>>>>>>
>>>>>>> USE_PYTHON=    2.5+
>>>>>>>
>>>>>>> Was there a specific reason for doing so?  I am running various
>>>>>>> tinderbox builds to check on port usage of the USE_PYTHON
>>>>>>> variable, and
>>>>>>> I noticed that devel/py-setuptools no longer builds if Python 2.4 is
>>>>>>> selected.
>>>>>>>
>>>>>>> I'd like to restore that capability, but before I send a PR, I
>>>>>>> wanted to
>>>>>>> check with you first.
>>>>>>>
>>>>>>> Thank you,
>>>>>>> Greg
>>>>>>> - --
>>>>>>> Greg Larkin
>>>>>>>
>>>>>>> http://www.FreeBSD.org/           - The Power To Serve
>>>>>>> http://www.sourcehosting.net/     - Ready. Set. Code.
>>>>>>> http://twitter.com/cpucycle/      - Follow you, follow me
>>>>>>
>>>>>> I'm sorry for sail in, but i think that the reason is that python24 is
>>>>>> reached it's EOL long time ago. Actually the only supported python
>>>>>> releases atm according to python.org are - 2.7.2 and 3.2.1, and
>>>>>> developers highly encourages the users to move to this versions.
>>>>>>
>>>>>> 2.5 and 2.6 are in security-fix-only mode, there will be no ANY
>>>>>> releases
>>>>>> for this branches after October 2011 and October 2013 respectively,
>>>>>> while 2.4 does not get security-fixes even.
>>>>>>
>>>>>> There is also this answer from Martin in this pr:
>>>>>> http://www.freebsd.org/cgi/query-pr.cgi?pr=ports/155526:
>>>>>>
>>>>>> python24 goes to the end of month, this port is on the todo for
>>>>>> removal
>>>>>>
>>>>>
>>>>> Hi Ruslan,
>>>>
>>>> Hi Greg
>>>>
>>>>>
>>>>> Ok, thank you for the explanation.  Shall I mark python24 for removal
>>>>> from the tree or file a PR for python@ to do it?
>>>>
>>>> It's not so easy actually, since we have many ports in the tree that
>>>> still depend on 2.4 (notably all that zope/plone stuff) and i believe it
>>>> was the reason why python24 still not be removed in the first place.
>>>> I do some work about eliminating python24 usage in the tree (yesterdays
>>>> py-pysqlite2x stuff - one of it), but it's not that fast. I also working
>>>> on porting zope2.13/plone4 (that supports python 2.6 and 2.7) and i'm
>>>> planing to finish it this weekend after proper testing. After that we
>>>> can deprecate/remove existing zope/plone (not longer supported
>>>> upstream).
>>>
>>> Ok, it's a bigger job than I realized!
>>>
>>>>
>>>>>
>>>>> FYI, I have been running tinderbox builds with PYTHON_VERSION and
>>>>> PYTHON_DEFAULT_VERSION set to python2.4, python2.5, etc. to find out if
>>>>> ports with USE_PYTHON=yes need to be constrained a bit more.
>>>>
>>>> Yes, there is a lot of work. We have USE_PYTHON with bogus values like
>>>> 1.5+, 1.6+, 2.0+ etc :). And most of python ports will not work with
>>>> python3x so they should be constrained with -2.7 too.
>>>
>>> Do you think it's helpful then to run these builds with different Python
>>> versions enforced?  I thought that getting the version ranges in the
>>> USE_PYTHON variable tightened up might help reduce the number of folks
>>> who run into build problems.  I would like to do the same thing with
>>> Perl, GCC, and others.
>>
>> I, personally, believe that this almost can't help to identify
>> version-specific problems, since commonly there is almost no build
>> problems on different python versions (it's rarely when setup.py
>> actually checking which python version it was run with). The problems
>> arises on runtime stage, when apps starting to import modules, that may
>> not exist in this particular python version or that installed by missing
>> dependencies, etc. Such problems may be identified only with manual
>> checking/greping/app docs reading. But this is just my point.
>> You'd better to ask Martin - he is committer that skilled with python
>> stuff in ports, and i'm not proper person to take responsibility for
>> decisions like that :). I just can to sound my point on this. However,
>> it definitely will help to identify gcc version-specific build problems.
>
> I have found some build problems with ports that use USE_PYTHON=yes
> instead of restricting it to a specific version, e.g.
>
>> copying build/lib/mpd.py ->  /usr/local/lib/python2.4/site-packages
>> byte-compiling /usr/local/lib/python2.4/site-packages/mpd.py to mpd.pyc
>>    File "/usr/local/lib/python2.4/site-packages/mpd.py", line 293
>>      yield retval()
>> SyntaxError: 'yield' not allowed in a 'try' block with a 'finally' clause
>> writing byte-compilation script '/tmp/tmpoLWlQC.py'
>> /usr/local/bin/python2.4 -O /tmp/tmpoLWlQC.py
>>    File "/usr/local/lib/python2.4/site-packages/mpd.py", line 293
>>      yield retval()
>> SyntaxError: 'yield' not allowed in a 'try' block with a 'finally' clause
>> removing /tmp/tmpoLWlQC.py
>> /bin/mkdir -p /usr/local/share/doc/py24-mpd
>
> Admittedly, this particular error was encountered while using Python 2.4
> as the default version, but I plan to run builds with all of the other
> versions looking for similar build problems.
>
> Regards,
> Greg

Ok, this particular error is well known and 24-specific:
http://docs.python.org/reference/simple_stmts.html
"""
As of Python version 2.5, the yield statement is now allowed in the try 
clause of a try ... finally construct. If the generator is not resumed 
before it is finalized (by reaching a zero reference count or by being 
garbage collected), the generator-iterator’s close() method will be 
called, allowing any pending finally clauses to execute.
"""

I checked the docs, i checked the code for audio/py-mpd - there is 
nothing about python versions. Authors just not assumed that anybody 
will try to run this code with 2.4. So may be it has the point to build 
such ports to check them. But i'd rather concentrate on eliminating 
explicit 24-specific consumers so we can deprecate lang/python24 to 
avoid such situations in principle.

And however, now we know that the left edge for SUE_PYTHON for this port 
would be 2.5+, but what about the right edge? Even if it will builds 
successfully with 3.x in tinderbox run, who can guarantee that it will 
RUN with 3.x?

-- 
Regards,
Ruslan

Tinderboxing kills... the drives.



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