Python-сообщество

    @classmethod
    @property
    def data_manager(cls):
        return cls.__connection__[cls.__objectname__]

cls.data_manager = property(...)

>>> class B(object):
...     def __get__(self, a, A):
...         if a is None:
...             return 'B'
...         return 'b'
    
>>> class A(object):
...     b = B()
    
>>> A.b
'B'
>>> A().b
'b'

class classproperty:
    def __init__(self, getter):
        self.__getter = getter
    def __get__(self, inst, owner):
        return self.__getter(owner)

class A:
    _x = 10
    @classproperty
    def data_manager(cls):
        return cls._x

>>> A.data_manager
10
>>> A().data_manager
10

class classproperty:
    def __init__(self, getter):
        print 'init'
        self.__getter = getter
    def __get__(self, inst, owner):
        print 'get'
        return self.__getter(owner)

class ActiveRecord(object):
    """
    """
    _test = 10
    @classproperty
    def data_manager(cls):
        return cls._test
#все остальные строки в классе закоментил
>>> ActiveRecord._test
10
ActiveRecord.data_manager
<rcms.base.activerecord.classproperty instance at 0x7f8c6eb11d88>