Why does object.__new__ with arguments work fine in Python 2.x and not in Python 3.3+? -

why following code work fine in python 2.x , not in python 3.3+:

class testa(object):     def __new__(cls, e):         return super(testa, cls).__new__(testb, e)  class testb(testa):     def __init__(self, e):         print(self, e)  testa(1) 

python 2.7.6 output:

(<__main__.testb object @ 0x7f6303378ad0>, 1) 

python 3.1.5 output:

__main__:3: deprecationwarning: object.__new__() takes no parameters <__main__.testb object @ 0x7f2f69db8f10> 1 

python 3.2.3 , 3.2.5 output:

<__main__.testb object @ 0xcda690> 1 

python 3.3.5 , 3.4.1 output:

traceback (most recent call last):   file "<stdin>", line 1, in <module>   file "<stdin>", line 3, in __new__ typeerror: object() takes no parameters 

object.__new__ has ignored arguments, , has issued deprecationwarning @ least since python 2.6.

the reason why aren't seeing deprecationwarning in 2.7 , 3.2 since 2.7 , 3.2 deprecationwarning has been suppressed default; if use python -wd or pythonwarnings=default see warning.

in python 3.3 deprecationwarning converted error.

the correct way write code (in version of python) swallow argument in testa.__new__:

class testa(object):     def __new__(cls, e):         return super(testa, cls).__new__(testb) 

since testb derived testa, argument will passed testb.__init__.