__reduce__(1) vs __reduce__(2)

[Kirill Simonov]

Could someone explain why __reduce__(2) works for files while
__reduce__(1) doesn't?

>>> f = file('/etc/passwd')
>>> f.__reduce__(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/lib/python2.4/copy_reg.py", line 69, in _reduce_ex
    raise TypeError, "can't pickle %s objects" % base.__name__
TypeError: can't pickle file objects
>>> f.__reduce__(2)
(<function __newobj__ at 0xb7e6317c>, (<type 'file'>,), None, None, None)

What is a correct procedure of getting state and restoring Python objects?

-- 
xi