[Python-Dev] On breaking modules into packages Was: [issue10199] Move Demo/turtle under Lib/ (original) (raw)

Michael Foord fuzzyman at voidspace.org.uk
Wed Nov 3 15:38:56 CET 2010

On 03/11/2010 14:26, Michael Foord wrote:

On 03/11/2010 14:17, Antoine Pitrou wrote:

Le mercredi 03 novembre 2010 à 14:16 +0000, Michael Foord a écrit :

On 03/11/2010 14:05, Nick Coghlan wrote:

On Wed, Nov 3, 2010 at 9:32 AM, Raymond Hettinger <raymond.hettinger at gmail.com> wrote:

Sounds like a decision to split a module into a package is a big commitment. Each of the individual file names becomes a permanent part of the API. Even future additional splits are precluded because it might break someones dotted import (i.e. not a single function can be moved between those files -- once in unittest.utils, alway in unittest.utils). Can Python 2.7 pickles containing unittest classes be unpickled using 2.6 or earlier? Even if nobody uses the new names for imports, I believe they implicitly end up included in any pickles involving affected classes (I seem to recall we've been bitten by that before when moving things around). Yes, since unittest.TestCase is still available (as are all the names). I believe so anyway... unittest.TestCase is not really pickleable. There were testmultiprocessing issues because of that (see recent SVN checkins). Interesting. We made some fixes before 2.7 to ensure they were copyable, but we fixed this in the copy module. TestCase instances now store some method objects in a dictionary which may make them unpickleable, so that could be a new problem. I'll test with 2.6 and 2.7 to see. An easy fix would be to store the method names rather than the method objects themself (if this is indeed the cause of the problem). This is what unittest2 does so that it works with earlier versions of Python that don't have the fix we put in copy. Yep, looks like 2.7 introduced a bug making it impossible to pickle TestCase instances. I think it will be easy to fix, I'll create a specific issue:

$python Python 2.6.5 (r265:79359, Mar 24 2010, 01:32:55) [GCC 4.0.1 (Apple Inc. build 5493)] on darwin Type "help", "copyright", "credits" or "license" for more information.

from unittest import TestCase from pickle import dumps t = TestCase('assert_') dumps(t) "ccopy_reg\n_reconstructor\np0\n(cunittest\nTestCase\np1\nc__builtin__\nobject\np2\nNtp3\nRp4\n(dp5\nS'_testMethodDoc'\np6\nS'Fail the test unless the expression is true.'\np7\nsS'testMethodName'\np8\nS'assert'\np9\nsb."

bigmac:beta.python.org michael$ python2.7 ActivePython 2.7.0.1 (ActiveState Software Inc.) based on Python 2.7 (r27:82500, Jul 4 2010, 13:58:56) [GCC 4.2.1 (Apple Inc. build 5664)] on darwin Type "help", "copyright", "credits" or "license" for more information.

from unittest import TestCase from pickle import dumps t = TestCase('assert_') dumps(t) Traceback (most recent call last): File "", line 1, in File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py", line 1374, in dumps Pickler(file, protocol).dump(obj) ... File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py", line 306, in save rv = reduce(self.proto) File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/copy_reg.py", line 70, in _reduce_ex raise TypeError, "can't pickle %s objects" % base.name TypeError: can't pickle instancemethod objects

All the best,

Michael

Michael

Regards

Antoine.

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