On 03/11/2010 14:53, Eric Smith wrote:
On 11/3/10 10:16 AM, Michael Foord wrote:
On 03/11/2010 14:05, Nick Coghlan wrote:
On Wed, Nov 3, 2010 at 9:32 AM, Raymond Hettinger
<raymond.hettin...@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...
Actually I think the answer is "no" (assuming you could pickle a
TestCase). Here's an example with TestLoader:
It is actually fixable by temporarily switching the __module__ attribute
of the classes inside a __reduce__ or __reduce_ex__ method. I couldn't
see a cleaner way of doing it using the pickling protocol methods. I
asked on #python-dev but the *only* person who claimed to understand the
pickle protocol methods was Barry, and he is clearly insane.
Antoine is firmly of the opinion that making TestCase instances
unpickleable is a feature...
Although in practise this is less likely to be an issue for TestCase
directly as it is extremely rare to use them without subclassing. More
likely to be an issue for the test result or runner objects.
All the best,
Michael Foord
$ python27
Python 2.7.0+ (release27-maint:85878, Oct 28 2010, 06:40:25)
[GCC 4.1.2 20070626 (Red Hat 4.1.2-13)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import unittest
>>> x = unittest.TestLoader()
>>> import pickle
>>> pickle.dumps(x)
'ccopy_reg\n_reconstructor\np0\n(cunittest.loader\nTestLoader\np1\nc__builtin__\nobject\np2\nNtp3\nRp4\n.'
>>>
$ python24
Python 2.4.4 (#1, Oct 23 2006, 13:58:00)
[GCC 4.1.1 20061011 (Red Hat 4.1.1-30)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>>
pickle.loads('ccopy_reg\n_reconstructor\np0\n(cunittest.loader\nTestLoader\np1\nc__builtin__\nobject\np2\nNtp3\nRp4\n.')
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.4/pickle.py", line 1394, in loads
return Unpickler(file).load()
File "/usr/lib/python2.4/pickle.py", line 872, in load
dispatch[key](self)
File "/usr/lib/python2.4/pickle.py", line 1104, in load_global
klass = self.find_class(module, name)
File "/usr/lib/python2.4/pickle.py", line 1138, in find_class
__import__(module)
ImportError: No module named loader
The problem is that there is no unittest.loader in 2.4, and
unittest.loader.TestLoader is the name that the 2.7 pickle creates. We
see this problem every time we try and move anything in the stdlib.
--
http://www.voidspace.org.uk/
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