work around Python bug #1569356

[Former user]

Under some circumstances, SQLAlchemy replaces instances of my declarative_base()-based class by one of 'propertyProxy' - which is originally defined as ''Proxy'' (you can verify this information by inserting ''raise self.!doc!'' in model.Member._set_password()).

I don't know the exact circumstances under which this occurs, but I know that running my test suite via a Continuous Integration System (such as Bitten) is one of them.

So I have created the minimum files required to reproduce the bug with Bitten, which I have attached as a compressed file. Please decompress the attached file and run:

# You may want to use a virtualenv for this.
# Installing Bitten:
easy_install http://svn.edgewall.org/repos/bitten/trunk/
# This has been tested with 0.5beta3:
easy_install "SQLAlchemy==0.5beta3"
# Now run my test suite via Bitten:
bitten-slave --keep-files --build-dir $PWD bitten-recipe.xml

You will get this error:

[   ](INFO) Traceback (most recent call last):                                                                                                                            
[   ](INFO)   File "/home/gustavo/Desktop/sa-bug/tests.py", line 36, in setUp                                                                                             
[   ](INFO)     self.member = Member(u"ignucius", u"hello world")
[   ](INFO)   File "<string>", line 4, in __init__
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/attributes.py", line 789, in initialize_instance
[   ](INFO)     fn(self, instance, args, kwargs)
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/mapper.py", line 1628, in _event_on_init
[   ](INFO)     instrumenting_mapper.compile()
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/mapper.py", line 369, in compile
[   ](INFO)     mapper.__initialize_properties()
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/mapper.py", line 390, in __initialize_properties
[   ](INFO)     prop.init(key, self)
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/interfaces.py", line 384, in init
[   ](INFO)     self.do_init()
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/properties.py", line 196, in do_init
[   ](INFO)     strategies.DefaultColumnLoader(self)._register_attribute(None, None, False, comparator_callable, proxy_property=self.descriptor)
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/strategies.py", line 39, in _register_attribute
[   ](INFO)     proxy_property=proxy_property
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/unitofwork.py", line 85, in register_attribute
[   ](INFO)     return attributes.register_attribute(class_, key, *args, **kwargs)
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/attributes.py", line 1429, in register_attribute
[   ](INFO)     descriptor = proxy_type(key, proxy_property, comparator, parententity)
[   ](INFO)   File "/home/gustavo/System/Pyenvs/tg2env/lib/python2.5/site-packages/SQLAlchemy-0.5.0beta3-py2.5.egg/sqlalchemy/orm/attributes.py", line 159, in __init__
[   ](INFO)     self.descriptor = self.user_prop = descriptor
[   ](INFO)   File "/home/gustavo/Desktop/sa-bug/model.py", line 54, in _set_password
[   ](INFO)     self._password = self.__class__._calculate_hash(password)
[   ](INFO) AttributeError: type object 'propertyProxy' has no attribute '_calculate_hash'

However, you won't get this error if you run the test suite directly:

python setup.py test

Please notice that this is not caused by Bitten: - If you check the environment variables with the two commands above (bitten-slave and `setup.py test'), you will find that they all have the same contents. - Bitten doesn't do anything special, it just runs distutils to run the ''test'' command.

Finally, please notice that I'm getting this error since I'm using ''synonym'' - everything was perfect before.

[Former user]

The files to reproduce this bug

[Former user]

Replying to guest:

Please notice that this is not caused by Bitten:

I mean, it should not.

[Mike Bayer]

the bug is in bitten. Remove model.py and replace tests.py with simply this code:

def foo(somearg):
    class Bar(object):
        def __getattr__(self, attribute):
            return getattr(somearg, attribute)

    assert 'somearg' not in Bar.__dict__

foo('hi')

run the bitten commandline, and it fails.

Please report this as a bug on the Bitten tracker.

[Mike Bayer]

according to http://bugs.python.org/issue1569356, this is a Python bug that is only fixed in 2.6. We should try working around it for python 2.5.

[Mike Bayer]

time moves on and 2.6 is commonplace. closing this for now.