copyreg doesn't support keyword only arguments in __new__

[erickt]

BPO	4727
Nosy	@jcea, @abalkin, @avassalotti, @serhiy-storchaka
Dependencies	bpo-17810: Implement PEP 3154 (pickle protocol 4)
Files	copy_getnewargs_ex.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 = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2015-03-24.16:08:11.720>
created_at = <Date 2008-12-23.02:35:02.277>
labels = ['type-feature', 'library']
title = "copyreg doesn't support keyword only arguments in __new__"
updated_at = <Date 2015-03-24.20:38:48.835>
user = 'https://bugs.python.org/erickt'

bugs.python.org fields:

activity = <Date 2015-03-24.20:38:48.835>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2015-03-24.16:08:11.720>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2008-12-23.02:35:02.277>
creator = 'erickt'
dependencies = ['17810']
files = ['38032']
hgrepos = []
issue_num = 4727
keywords = ['patch']
message_count = 7.0
messages = ['78222', '109264', '109266', '204973', '235503', '239178', '239179']
nosy_count = 6.0
nosy_names = ['jcea', 'belopolsky', 'alexandre.vassalotti', 'erickt', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue4727'
versions = ['Python 3.5']

[erickt]

According to both of these bugs:

http://bugs.python.org/issue1398
http://bugs.python.org/issue4331

pickle can't pickle functools.partial objects. It looks the underlying
reason is that objects that pickle can't handle objects with __new__ and
keyword only arguments. To support this, would this require a new pickle
protocol and a __getnewfullargs__ that returns a tuple and dict?

[BreamoreBoy]

http://bugs.python.org/issue1398 has already been fixed and closed.
http://bugs.python.org/issue4331 is still open and has seen activity as recently as 2010-02-23, so can this be closed or must it remain open?

[abalkin]

Please keep this open. This issue is separate from pickling partial objects.

[avassalotti]

PEP-3154 implemented support for pickling classes taking keyword-only arguments.

The copy module should be updated to use __getnewargs_ex__ when available through object.__reduce__(4).

[serhiy-storchaka]

Here is a patch.

[python-dev]

New changeset 83cbf61a972b by Serhiy Storchaka in branch 'default':
Issue bpo-4727: Fixed issue number in Misc/NEWS.
https://hg.python.org/cpython/rev/83cbf61a972b

[serhiy-storchaka]

The patch actually was committed in changeset 34930a6faf0d.