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configparser does not convert defaults to strings #68023

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configparser does not convert defaults to strings#68023
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3.7 (EOL)end of lifedeferred-blockerstdlibStandard Library Python modules in the Lib/ directorytype-bugAn unexpected behavior, bug, or error

Description

@aragilar
aragilar
mannequin
opened on Apr 1, 2015
BPO 23835
Nosy @warsaw, @vstinner, @bitdancer, @ambv, @aragilar, @asottile, @miss-islington, @junyixie
PRs
  • bpo-23835: Enforce that configparser defaults are strings #2558
  • bpo-23835: [docs] configparser converts defaults to strings #3176
  • bpo-23835: Restore legacy defaults= behavior for RawConfigParser #3191
  • bpo-33802: Do not interpolate in ConfigParser while reading defaults #7524
  • [3.7] bpo-33802: Do not interpolate in ConfigParser while reading defaults (GH-7524) #7529
    		•
    Files
  • py27-config-fix.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 2018-06-08.17:10:28.583>
created_at = <Date 2015-04-01.04:23:08.378>
labels = ['3.7', 'deferred-blocker', 'type-bug', 'library']
title = 'configparser does not convert defaults to strings'
updated_at = <Date 2021-03-13.13:23:31.799>
user = 'https://github.com/aragilar'

    bugs.python.org fields:

    activity = <Date 2021-03-13.13:23:31.799>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2018-06-08.17:10:28.583>
closer = 'barry'
components = ['Library (Lib)']
creation = <Date 2015-04-01.04:23:08.378>
creator = 'aragilar'
dependencies = []
files = ['38861']
hgrepos = []
issue_num = 23835
keywords = ['patch', '3.7regression']
message_count = 16.0
messages = ['239768', '240249', '297793', '298205', '298234', '298279', '300660', '300661', '300717', '300791', '318983', '318999', '319047', '319066', '320899', '323285']
nosy_count = 8.0
nosy_names = ['barry', 'vstinner', 'r.david.murray', 'lukasz.langa', 'aragilar', 'Anthony Sottile', 'miss-islington', 'JunyiXie']
pr_nums = ['2558', '3176', '3191', '7524', '7529']
priority = 'deferred blocker'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue23835'
versions = ['Python 3.7']

    Activity

    1. aragilar commented on Apr 1, 2015

      @aragilar
      aragilarmannequin
      on Apr 1, 2015
      MannequinAuthor

      ConfigParser(defaults={1:2.4}) and ConfigParser(defaults={"a":5.2}) cause an exception when configparser tries to perform string operations on 1 and 5.2. I didn't see it documented that defaults must only contain strings, and using ConfigParser['DEFAULT'] = {1:2.4} does the necessary string conversion, so it looks like there should be some conversion done to the defaults.

    2. Imagearagilar
      added
      type-crashA hard crash of the interpreter, possibly with a core dump
      stdlibStandard Library Python modules in the Lib/ directory
      on Apr 1, 2015
    3. Imageserhiy-storchaka
      added
      type-bugAn unexpected behavior, bug, or error
      and removed
      type-crashA hard crash of the interpreter, possibly with a core dump
      on Apr 1, 2015

    4. aragilar commented on Apr 8, 2015

      @aragilar
      aragilarmannequin
      on Apr 8, 2015
      MannequinAuthor

      Here's a patch for 2.7 (based of the head of the 2.7 branch), something similar could be done for 3.4 (I wasn't sure what branch I was supposed to base the patch off, since 3.4 is inactive). The string requirement was already noted in the docstring of the configparser module, but that's not mentioned in the main docs. Also, I wasn't sure where to put a test in because there was not test_configparser.py located in Lib/test.

    5. bitdancer commented on Jul 6, 2017

      @bitdancer
      bitdancer
      on Jul 6, 2017
      Member

      I'm guessing we can only do something here in 3.7, for backward compatibility reasons, but maybe I'm wrong. Hopefully Lukasz will notice the activity on the issue and have time to take a look.

    6. Imagebitdancer
      added
      3.7 (EOL)end of life
      on Jul 6, 2017

    7. ambv commented on Jul 12, 2017

      @ambv
      ambv
      on Jul 12, 2017
      Contributor

      Responded on the PR.

    8. bitdancer commented on Jul 12, 2017

      @bitdancer
      bitdancer
      on Jul 12, 2017
      Member

      Thanks. OK, so you agree a fix is appropriate. What about the question of backport/backward compatibility?

    9. ambv commented on Jul 13, 2017

      @ambv
      ambv
      on Jul 13, 2017
      Contributor

      Backwards compatibility will be considered when the patch is ready. I'm not overly worried about fixing a case that currently raises exceptions all over the place. There's few compatibility concerns that we need to consider in this case.

    10. ambv commented on Aug 21, 2017

      @ambv
      ambv
      on Aug 21, 2017
      Contributor

      New changeset 44e6ad8 by Łukasz Langa (James Tocknell) in branch 'master':
      bpo-23835: Enforce that configparser defaults are strings (bpo-2558)
      44e6ad8

    11. ambv commented on Aug 21, 2017

      @ambv
      ambv
      on Aug 21, 2017
      Contributor

      New changeset ea57923 by Łukasz Langa in branch 'master':
      bpo-23835: [docs] configparser converts defaults to strings (bpo-3176)
      ea57923

    12. ambv commented on Aug 22, 2017

      @ambv
      ambv
      on Aug 22, 2017
      Contributor

      I merged the original fix and documented it. I thought about it some more and remembered that RawConfigParser objects do in fact support non-string values by historical coincidence. It's unfortunately a popular idiom with old programs to load some configuration defaults using the defaults= keyword and later use the legacy get() and set() API which doesn't check types inside. A config file like this cannot be safely written back to a file, etc.

      I would very much like to get rid of RawConfigParser entirely but we're stuck with it due to backwards compatibility. So, to fix the regression, I created PR 3191.

    13. ambv commented on Aug 24, 2017

      @ambv
      ambv
      on Aug 24, 2017
      Contributor

      New changeset a5fab17 by Łukasz Langa in branch 'master':
      bpo-23835: Restore legacy defaults= behavior for RawConfigParser (bpo-3191)
      a5fab17

    14. Imageambv
      closed this as completedon Aug 27, 2017

    15. warsaw commented on Jun 7, 2018

      @warsaw
      warsaw
      on Jun 7, 2018
      Member

      I think this introduced a regression in 3.7. See bpo-33802

      https://bugs.python.org/issue33802

    16. Imagewarsaw
      reopened this on Jun 7, 2018
    17. Imagewarsaw
      added
      deferred-blocker
      on Jun 7, 2018

    18. vstinner commented on Jun 8, 2018

      @vstinner
      vstinner
      on Jun 8, 2018
      Member

      It seems like this issue introduced a regression according to Barry: bpo-33802.

    19. ambv commented on Jun 8, 2018

      @ambv
      ambv
      on Jun 8, 2018
      Contributor

      New changeset 214f18e by Łukasz Langa in branch 'master':
      bpo-33802: Do not interpolate in ConfigParser while reading defaults (GH-7524)
      214f18e

    20. miss-islington commented on Jun 8, 2018

      @miss-islington
      miss-islington
      on Jun 8, 2018
      Contributor

      New changeset f44203d by Miss Islington (bot) in branch '3.7':
      bpo-33802: Do not interpolate in ConfigParser while reading defaults (GH-7524)
      f44203d

    21. Imagewarsaw
      closed this as completedon Jun 8, 2018

    22. asottile commented on Jul 2, 2018

      @asottile
      asottilemannequin
      on Jul 2, 2018
      Mannequin

      Unclear if this regression (from this patch) is intentional or not:

      $ python3.6 -c 'import configparser; configparser.ConfigParser(defaults={"a": None})'
$ python3.7 -c 'import configparser; configparser.ConfigParser(defaults={"a": None})'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/configparser.py", line 638, in __init__
    self._read_defaults(defaults)
  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/configparser.py", line 1216, in _read_defaults
    self.read_dict({self.default_section: defaults})
  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/configparser.py", line 753, in read_dict
    self.set(section, key, value)
  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/configparser.py", line 1197, in set
    self._validate_value_types(option=option, value=value)
  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/configparser.py", line 1182, in _validate_value_types
    raise TypeError("option values must be strings")
TypeError: option values must be strings

    23. ambv commented on Aug 8, 2018

      @ambv
      ambv
      on Aug 8, 2018
      Contributor

      That's intentional. In ConfigParser objects this exception would be raised for any other section's assignment already. You want RawConfigParser if you want to put (invalid) types as option values. See:

      >>> cp = ConfigParser()
>>> cp['asd'] = {'a': None}
Traceback (most recent call last):
...
TypeError: option values must be strings
>>> rcp = RawConfigParser()
>>> rcp['asd'] = {'a': None}
>>>
    24. Imageezio-melotti
      transferred this issue fromon Apr 10, 2022
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