Description

hugovk

opened on Feb 2, 2022

Issue body actions

BPO	46607
Nosy	@gpshead, @vstinner, @ambv, @hugovk
PRs	bpo-46607: Add DeprecationWarning to LegacyInterpolation #30927

^{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 2022-04-05.22:08:56.439>
created_at = <Date 2022-02-02.07:01:09.212>
labels = ['library', '3.11']
title = "Add DeprecationWarning to configparser's LegacyInterpolation"
updated_at = <Date 2022-04-05.22:08:56.438>
user = 'https://github.com/hugovk'

bugs.python.org fields:

activity = <Date 2022-04-05.22:08:56.438>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2022-04-05.22:08:56.439>
closer = 'vstinner'
components = ['Library (Lib)']
creation = <Date 2022-02-02.07:01:09.212>
creator = 'hugovk'
dependencies = []
files = []
hgrepos = []
issue_num = 46607
keywords = ['patch']
message_count = 5.0
messages = ['412339', '412347', '412391', '416785', '416822']
nosy_count = 4.0
nosy_names = ['gregory.p.smith', 'vstinner', 'lukasz.langa', 'hugovk']
pr_nums = ['30927']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue46607'
versions = ['Python 3.11']

Activity

1. hugovk commented on Feb 2, 2022

   

   hugovk

   on Feb 2, 2022

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   The LegacyInterpolation class of configparser has been deprecated in docs since 3.2, but without raising a DeprecationWarning.

   The 3.2 HISTORY file says:

   • configparser: the SafeConfigParser class has been renamed to ConfigParser.
     The legacy ConfigParser class has been removed but its interpolation mechanism is still available as LegacyInterpolation.

   Searching the top 5,000 PyPI sdists, there's very little (if any "real") use of LegacyInterpolation. Details: https://bugs.python.org/issue45173#msg409685

   Other configparser deprecations were added in 3.2, but with DeprecationWarnings.

   Let's add a DeprecationWarning for a couple of releases before removal.
2. hugovk

   added

   3.11only security fixesonly security fixes

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

   on Feb 2, 2022
3. vstinner commented on Feb 2, 2022

   

   vstinner

   on Feb 2, 2022

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   Oh, LegacyInterpolation is not documented at:
   https://docs.python.org/dev/library/configparser.html

   Other configparser deprecations were added in 3.2, but with DeprecationWarnings.

   Its deprecation was never documented anywhere in Doc/.

   Well, to respect the PEP-387, the class should emit a DeprecationWarning and its depreaction must be documented in What's New in Python 3.11.

   The LegacyInterpolation class of configparser has been deprecated in docs since 3.2, but without raising a DeprecationWarning.

   I found the following change:

   commit 7f64c8a5121576fd8f92010b7a936b89581c4051
   Author: Łukasz Langa \<[email protected]\>
   Date:   Thu Dec 16 01:16:22 2010 +0000
   
       Broken ConfigParser removed, SafeConfigParser renamed to ConfigParser.
       Life is beatiful once again.
   

   It renamed BrokenInterpolation to LegacyInterpolation:

   -class BrokenInterpolation(Interpolation):
   -    """Deprecated interpolation as implemented in the classic ConfigParser.
   +class LegacyInterpolation(Interpolation):
   +    """Deprecated interpolation used in old versions of ConfigParser.

   The BrokenInterpolation class was added by bpo-10499:

   commit b6a6f5f886ed869612e16cd1e29a1190996dc78d
   Author: Łukasz Langa \<[email protected]\>
   Date:   Fri Dec 3 16:28:00 2010 +0000
   
       bpo-10499: Modular interpolation in configparser
   

   It would be nice to have Łukasz's opinion on deprecating LegacyInterpolation.

   The configparser.RawConfigParser has an "interpolation" parameter and configparser.RawConfigParser._DEFAULT_INTERPOLATION is an instance of configparser.Interpolation:

       # Interpolation algorithm to be used if the user does not specify another        
       _DEFAULT_INTERPOLATION = Interpolation()                                       

   If the BrokenInterpolation is removed in Python 3.13 and a project is affected by the removal, can it simply copy/paste the Python 3.12 copy in its project and continue using the class? configparser.Interpolation seems to be a clean ABC class, so it seems safe to copy/paste the code. It doesn't seem to depend on anything but configparser.Interpolation which is public (even if it's not documented).

   https://bugs.python.org/issue45173#msg409685:

   Searching 4,764 sdists from the top 5,000 PyPI packages, these 13 contain "LegacyInterpolation": (...)
   two are stdlib backports: (...)
   The others are all configparser.pyi typeshed stub files: (...)

   I understand that *in practice*, removing the class would impact no project of the top 5000 PyPI projects. Thanks for checking!
4. hugovk commented on Feb 2, 2022

   

   hugovk

   on Feb 2, 2022

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   > Other configparser deprecations were added in 3.2, but with DeprecationWarnings.

   Its deprecation was never documented anywhere in Doc/.

   Correct, only in the docstring:

   class LegacyInterpolation(Interpolation):
       """Deprecated interpolation used in old versions of ConfigParser.
       Use BasicInterpolation or ExtendedInterpolation instead."""
   

   I've updated #75110 to say "deprecated in the docstring" instead of "deprecated in docs".
5. gpshead commented on Apr 5, 2022

   

   gpshead

   on Apr 5, 2022

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   New changeset 7528094 by Hugo van Kemenade in branch 'main':
   bpo-46607: Add DeprecationWarning for LegacyInterpolation, deprecated in docs since 3.2 (GH-30927)
   7528094
6. vstinner commented on Apr 5, 2022

   

   vstinner

   on Apr 5, 2022

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   Thanks Hugo for the your contribution. I close the issue.

   Searching the top 5,000 PyPI sdists, there's very little (if any "real") use of LegacyInterpolation. Details: https://bugs.python.org/issue45173#msg409685

   You can offer them a PR to avoid the deprecated API, or at least notify them by creating an issue that this API is deprecated in Python 3.11.
7. vstinner

   closed this as completedon Apr 5, 2022
8. vstinner

   closed this as completedon Apr 5, 2022
9. ezio-melotti

   transferred this issue fromon Apr 10, 2022
10. JelleZijlstra

    added a commit that references this issue on May 2, 2022

    gh-90765: configparser test: Catch deprecation warning (#91480)

    56f9844

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