frozenset, when subclassed will yield warning upon call to super(...).__init__(iterable)

[carstenkleinaxn-softwarede]

BPO	9659
Nosy	@rhettinger, @benjaminp, @merwok

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2010-08-22.15:34:30.530>
created_at = <Date 2010-08-22.14:42:19.952>
labels = ['interpreter-core', 'type-bug', 'invalid']
title = 'frozenset, when subclassed will yield warning upon call to super(...).__init__(iterable)'
updated_at = <Date 2010-08-25.13:34:29.440>
user = 'https://bugs.python.org/carstenkleinaxn-softwarede'

bugs.python.org fields:

activity = <Date 2010-08-25.13:34:29.440>
actor = 'benjamin.peterson'
assignee = 'none'
closed = True
closed_date = <Date 2010-08-22.15:34:30.530>
closer = 'benjamin.peterson'
components = ['Interpreter Core']
creation = <Date 2010-08-22.14:42:19.952>
creator = 'carsten.klein@axn-software.de'
dependencies = []
files = []
hgrepos = []
issue_num = 9659
keywords = []
message_count = 7.0
messages = ['114676', '114677', '114678', '114680', '114683', '114889', '114904']
nosy_count = 5.0
nosy_names = ['rhettinger', 'benjamin.peterson', 'stutzbach', 'eric.araujo', 'carsten.klein@axn-software.de']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue9659'
versions = ['Python 2.6']

[carstenkleinaxn-softwarede]

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.

[merwok]

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?

[stutzbach]

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.

[benjaminp]

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

[rhettinger]

Thanks Benjamin. I concur with your conclusion.

[carstenkleinaxn-softwarede]

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

[benjaminp]

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__