Python super() behavior not dependable

Are you reloading modules somehow in the middle of things? If so, that may explain this error.

isinstance(self,DBAdminConnection) may become false after reloading modules because of the changes to memory references, apparently.

Edit: if you're running your web.py app under mod_wsgi, make sure you're disabling autoreload:

app = web.application(urls, globals(), autoreload=False)

If you are using reload() as part of your workflow, you apparently need to also use super(self.__class__, self).__init__ for inheritance initialization.

I suspect you will find this bug coincides with id(self.__class__) ==id(Retrieval) failing.

I'm not sure why the error is happening, but as an aid to debugging you could wrap the call to super in a try/except block and do a data dump when the exception is raised. Something like this:

class Retrieval(DBConnection.DBAdminConnection):     def __init__(self, username=None, password=None, unique_key=None):        try:            super(Retrieval,self).__init__()        except TypeError, e:            print "Failure initialising Retrieval --> self: %r"            raise        if username and password:            self.username = username            self.user.login(username,password, config.DATABASE)            if self.user.error:                raise UserLoginError(username)        self.unique_key = unique_key