.pyc file / with_metaclass thing between 0.8/0.9 - needs more detail

[jeroen_stevens]

After updating SQLAlchemy to 0.9.2 i got this error:

Traceback (most recent call last):
  File "/home/vagrant/test/api/app/database/__init__.py", line 1, in <module>
    from sqlalchemy import create_engine
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/__init__.py", line 50, in <module>
    from .types import (
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/types.py", line 26, in <module>
    from . import exc, schema, util, processors, events, event
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/schema.py", line 33, in <module>
    from . import exc, util, dialects, event, events, inspection
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/event/__init__.py", line 7, in <module>
    from .api import CANCEL, NO_RETVAL, listen, listens_for, remove, contains
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/event/api.py", line 13, in <module>
    from .base import _registrars
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/event/base.py", line 152, in <module>
    class Events(util.with_metaclass(_EventMeta, object)):
AttributeError: 'module' object has no attribute 'with_metaclass'

In version 0.8

class Events(util.with_metaclass(_EventMeta, object))

this existed in multiple files and now in 0.9.2 only in the base.py file so I tried to change it to

class Events(object):

That resulted in:

  File "/home/vagrant/shuffler/api/app/database/__init__.py", line 1, in <module>
    from sqlalchemy import create_engine
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/__init__.py", line 50, in <module>
    from .types import (
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/types.py", line 26, in <module>
    from . import exc, schema, util, processors, events, event
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/schema.py", line 33, in <module>
    from . import exc, util, dialects, event, events, inspection
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/events.py", line 220, in <module>
    class SchemaEventTarget(object):
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/events.py", line 227, in SchemaEventTarget
    dispatch = event.dispatcher(DDLEvents)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/event/base.py", line 209, in __init__
    self.dispatch_cls = events.dispatch
AttributeError: type object 'DDLEvents' has no attribute 'dispatch'

I don't know where to look anymore.

[Mike Bayer]

OK a little puzzling here is that you're saying the "with_metaclass" thing is in 0.8, which is not the case, that's in 0.9. In 0.8 we have the usual __metaclass__ attribute.

When I switch the files in place from 0.9 to 0.8 I get this error, until the .pyc files are deleted.

So it's a little unclear here if you are in fact going from 0.8 to 0.9, or 0.9 back to 0.8 which is where this is observed, but I think what you need to do is just delete the .pyc files.

if you can confirm this is from 0.9 down to 0.8, not the other way around, I can maybe try to figure out the exact nature of why this happens though people have generally not been reporting it, I think typically using pip/setuptools prevents this kind of thing from happening.

[jeroen_stevens]

Sorry for the confusing. Today i updated from 0.8.0 (when everything was fine) to 0.9.2. That is when i got the error. Now i've set it back to 0.8.0 just because I knew that was the latest version it was still working on.

So I should just delete all the .pyc files from the sqlalchemy directory?

[Mike Bayer]

how are you installing this? SQLA 0.9.2 has the "util.with_metaclass" call, 0.8 does not. you should not get any errors upgrading from 0.8 to 0.9.2. Can you please start with a fresh install of 0.9.2, ensure no .py or .pyc files are present first, then see if 0.9.2 produces an error (and if it does, what is the exact error?)

[jeroen_stevens]

just

sudo pip install SQLAlchemy

Now I uninstalled all versions of SQLAlchemy with:

sudo pip uninstall SQLAlchemy

followed by:

sudo pip install SQLAlchemy # (again)

and now everything is just running smoothly again!

Hmm, there probably went something wrong with the installation the first time when I installed 0.9.2. No idea what it could have been though.

But many thanks for your support!! Now I can finally continue.

[Mike Bayer]

alright just going to close this, there's definitely weirdness with .pyc files but typically it shouldnt affect people

[Mike Bayer]

Removing milestone: 0.9.2 (automated comment)