Example

class a(frozenset):
    def __init__(self, iterable):
        super(a, self).__init__(iterable)


i = a([1,2,3])
> __main__:3: DeprecationWarning: object.__init__() takes no parameters
> a([1, 2, 3])


This might be due to the fact that the frozenset type structure does not initialize the tp_init field in setobject.c, thus inheriting the original __init__ from object.

Subclassing set will not issue that warning as it actually defines the tp_init field to (initroc)set_init.

This holds true also for the Python 2.7 release and maybe also later releases.

Expected behaviour: do not output that warning message and provide an initproc for the tp_field.

Thank you for the report. 2.6 is in security mode, it does not get bug fixes anymore. Can you reproduce the bug with 2.7, 3.1 and 3.2?

I can reproduce it in Python 3.1 and 3.2  I don't have a build of Python 2.7 handy at the moment to test it there.

In Python 3.2 and 2.7, DeprecationWarnings are silenced by default.  I had to start Python 3.2 with "-W always::DeprecationWarning" to see the problem.

This is correct. immutable types should use __new__, not __init__.

Thanks Benjamin.  I concur with your conclusion.

Thanks for the information. Where is this documented? I cannot find it in the official Python docs... TIA.

2010/8/25 Carsten Klein <report@bugs.python.org>:
>
> Carsten Klein <carsten.klein@axn-software.de> added the comment:
>
> Thanks for the information. Where is this documented? I cannot find it in the official Python docs... TIA.

http://docs.python.org/dev/reference/datamodel.html#object.__new__