>>> class A(object):
...     def __init__(self, *args, **kwargs):
...         if self.foo != 42:
...             raise Exception("You get the answer and than call me, KAPISH?")
...     @classmethod
...     def simpleconstructor(cls, *args, **kwargs):
...         return object.__new__(cls, *args, **kwargs)
...
>>> A.simpleconstructor()
<__main__.A object at 0xb7d705ac>
>>> A()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in __init__
AttributeError: 'A' object has no attribute 'foo'