Description

assignee = None
closed_at = None
created_at = <Date 2018-03-06.05:36:52.125>
labels = ['3.8', 'library', '3.9', '3.10']
title = 'Objects referencing private-mangled names do not roundtrip properly under pickling.'
updated_at = <Date 2020-07-15.17:51:11.385>
user = 'https://github.com/anntzer'

activity = <Date 2020-07-15.17:51:11.385>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2018-03-06.05:36:52.125>
creator = 'Antony.Lee'
dependencies = []
files = []
hgrepos = []
issue_num = 33007
keywords = ['patch']
message_count = 2.0
messages = ['313306', '349838']
nosy_count = 5.0
nosy_names = ['alexandre.vassalotti', 'serhiy.storchaka', 'Antony.Lee', 'josh.r', 'ZackerySpytz']
pr_nums = ['21480']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue33007'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

Activity

1. anntzer commented on Mar 6, 2018

   

   anntzermannequin

   on Mar 6, 2018

   MannequinAuthor

   More actions

   Consider the following example:

       import pickle
   
       class T:
           def __init__(self):
               self.attr = self.__foo
   
           def __foo(self):
               pass
   
       print(pickle.loads(pickle.dumps(T())))

   This fails on 3.6 with AttributeError: 'T' object has no attribute '__foo' (i.e. there's a lookup on the unmangled name). As a comparison, replacing __foo with _foo results in working code.
2. anntzer

   added

   3.7 (EOL)end of lifeend of life

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   on Mar 6, 2018
3. MojoVampire commented on Aug 16, 2019

   

   MojoVampiremannequin

   on Aug 16, 2019

   Mannequin

   More actions

   This problem is specific to private methods AFAICT, since they're the only things which have an unmangled __name__ used to pickle them, but are stored as a mangled name.

   More details on cause and solution on issue bpo-37852, which I closed as a duplicate of this issue.
4. MojoVampire

   added

   3.8 (EOL)end of lifeend of life

   3.9 (EOL)end of lifeend of life

   on Aug 16, 2019
5. serhiy-storchaka

   added

   3.10 (EOL)end of lifeend of life

   and removed

   3.7 (EOL)end of lifeend of life

   on Jul 15, 2020
6. ezio-melotti

   transferred this issue fromon Apr 10, 2022
7. serhiy-storchaka

   added this to Pickle and copy issues 🥒on May 19, 2022
8. joeyagreco commented on Jul 8, 2022

   

   joeyagreco

   on Jul 8, 2022

   More actions

   Having this same issue on Python 3.10. Any updates on this?
9. nanjekyejoannah commented on Oct 7, 2022

   

   nanjekyejoannah

   on Oct 7, 2022

   Contributor

   More actions

   @joeyagreco We have a PR if the author fixes, I can merge after some verification.
10. ZackerySpytz commented on Dec 11, 2022

    

    ZackerySpytz

    on Dec 11, 2022

    Contributor

    More actions

    @nanjekyejoannah I have fixed the PR's merge conflicts.
11. hugovk

    removed

    3.10 (EOL)end of lifeend of life

    3.9 (EOL)end of lifeend of life

    on Apr 7, 2023
12. 13 remaining items
13. serhiy-storchaka

    added

    3.15bugs and security fixesbugs and security fixes

    on Jan 6, 2026
14. serhiy-storchaka commented on Jan 6, 2026

    

    serhiy-storchaka

    on Jan 6, 2026

    Member

    More actions

    Since this never worked before, I reclassify this as a new feature.

    #21480 only handles private bound methods. Staticmethods, classmethods and unbound methods are not supported.
15. serhiy-storchaka

    self-assigned this

    on Jan 6, 2026
16. serhiy-storchaka

    added 2 commits that reference this issue on Jan 21, 2026

    pythongh-77188: Add pickle tests for objects with slots

    dd48ef4

    gh-77188: Add pickle tests for objects with slots (GH-144116)

    cf71e34
17. miss-islington

    added 2 commits that reference this issue on Jan 21, 2026

    pythongh-77188: Add pickle tests for objects with slots (pythonGH-144116

    83148d5

    pythongh-77188: Add pickle tests for objects with slots (pythonGH-144116

    708e9c9
18. serhiy-storchaka

    added 2 commits that reference this issue on Jan 21, 2026

    [3.14] gh-77188: Add pickle tests for objects with slots (GH-144116) (G…

    a74709d

    [3.13] gh-77188: Add pickle tests for objects with slots (GH-144116) (G…

    ac9715b
19. serhiy-storchaka

    closed this as completedon Feb 5, 2026
20. github-project-automation

    moved this to Done in Pickle and copy issues 🥒on Feb 5, 2026
21. serhiy-storchaka

    added a commit that references this issue on Feb 5, 2026

    gh-77188: Add support for pickling private methods and nested classes (…

    01a1dd2
22. thunder-coding

    added 2 commits that reference this issue on Feb 15, 2026

    pythongh-77188: Add pickle tests for objects with slots (pythonGH-144116

    15f4923

    pythongh-77188: Add support for pickling private methods and nested c…

    672ba32
23. ljfp

    added a commit that references this issue on Apr 25, 2026

    pythongh-77188: Add support for pickling private methods and nested c…

    c321be9

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