Constructors of weakref mapping classes don't accept "self" and "dict" keyword arguments

[serhiy-storchaka]

BPO	22958
Nosy	@freddrake, @rhettinger, @pitrou, @benjaminp, @serhiy-storchaka
Dependencies	bpo-22609: Constructors of some mapping classes don't accept self keyword argument
Files	WeakValueDictionary_pos_only_params.patch

^{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 2015-09-29.21:00:08.017>
created_at = <Date 2014-11-27.16:13:23.539>
labels = ['type-bug', 'library']
title = 'Constructors of weakref mapping classes don\'t accept "self" and "dict" keyword arguments'
updated_at = <Date 2015-09-29.21:00:08.016>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2015-09-29.21:00:08.016>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2015-09-29.21:00:08.017>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2014-11-27.16:13:23.539>
creator = 'serhiy.storchaka'
dependencies = ['22609']
files = ['37395']
hgrepos = []
issue_num = 22958
keywords = ['patch', 'needs review']
message_count = 4.0
messages = ['231767', '232358', '238694', '251885']
nosy_count = 6.0
nosy_names = ['fdrake', 'rhettinger', 'pitrou', 'benjamin.peterson', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue22958'
versions = ['Python 2.7', 'Python 3.4', 'Python 3.5']

[serhiy-storchaka]

Dict-like types in the weakref module (WeakValueDictionary and WeakKeyDictionary) don't allow to specify key-value pair as keyword arguments if key is "self" or "dict".

>>> import weakref
>>> class A: pass
... 
>>> a = A()
>>> d = weakref.WeakValueDictionary(spam=a)
>>> list(d.items())
[('spam', <__main__.A object at 0xb6f3f88c>)]
>>> weakref.WeakValueDictionary(self=a)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: __init__() got multiple values for argument 'self'
>>> weakref.WeakValueDictionary(dict=a)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/serhiy/py/cpython/Lib/weakref.py", line 114, in __init__
    self.update(*args, **kw)
  File "/home/serhiy/py/cpython/Lib/weakref.py", line 261, in update
    dict = type({})(dict)
TypeError: 'A' object is not iterable
>>> d = weakref.WeakValueDictionary()
>>> d.update(spam=a)
>>> list(d.items())
[('spam', <__main__.A object at 0xb6f3f88c>)]
>>> d.update(self=a)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: update() got multiple values for argument 'self'
>>> d.update(dict=a)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/serhiy/py/cpython/Lib/weakref.py", line 261, in update
    dict = type({})(dict)
TypeError: 'A' object is not iterable

Related issue for the collections module is bpo-22609. I think weakref mapping classes should be fixed in the same manner.

[serhiy-storchaka]

Here is a patch similar to patch from bpo-22609 which makes WeakValueDictionary constructor and update accept keyword arguments "self" and "dict".

[benjaminp]

lgtm

[python-dev]

New changeset 8274fc521e69 by Serhiy Storchaka in branch '2.7':
Issue bpo-22958: Constructor and update method of weakref.WeakValueDictionary
https://hg.python.org/cpython/rev/8274fc521e69

New changeset 01c79072d671 by Serhiy Storchaka in branch '3.4':
Issue bpo-22958: Constructor and update method of weakref.WeakValueDictionary
https://hg.python.org/cpython/rev/01c79072d671

New changeset 73b6b88ac28a by Serhiy Storchaka in branch '3.5':
Issue bpo-22958: Constructor and update method of weakref.WeakValueDictionary
https://hg.python.org/cpython/rev/73b6b88ac28a

New changeset 815bb6a2d69e by Serhiy Storchaka in branch 'default':
Issue bpo-22958: Constructor and update method of weakref.WeakValueDictionary
https://hg.python.org/cpython/rev/815bb6a2d69e