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GeezerVison is showing github.com — gh-118150: warn in doc about results asymmetry for difflib junk by Lenormju · Pull Request #153892 · python/cpython

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@Lenormju

@Lenormju Lenormju commented Jul 18, 2026 •
edited by bedevere-app Bot
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Contributor
  • Issue: Difflib creates unreasonably large diffs #118150

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@Lenormju
docs: warn about results asymmetry for difflib junk
f6e54c2
@python-cla-bot

python-cla-bot Bot commented Jul 18, 2026 •
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All commit authors signed the Contributor License Agreement.

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@bedevere-app bedevere-app Bot added the docs Documentation in the Doc dir label Jul 18, 2026
@github-project-automation github-project-automation Bot added this to Docs PRs Jul 18, 2026
@github-project-automation github-project-automation Bot moved this to Todo in Docs PRs Jul 18, 2026
@bedevere-app bedevere-app Bot added the awaiting review label Jul 18, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Jul 18, 2026
Difflib creates unreasonably large diffs #118150
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@read-the-docs-community

read-the-docs-community Bot commented Jul 18, 2026 •
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Documentation build overview

📚 cpython-previews | 🛠️ Build #33647276 | 📁 Comparing 0793740 against main (cffcee4)

  🔍 Preview build  

16 files changed · ± 16 modified

± Modified

  • c-api/frame.html
  • c-api/veryhigh.html
  • library/allos.html
  • library/calendar.html
  • library/concurrent.interpreters.html
  • library/ctypes.html
  • library/difflib.html
  • library/filecmp.html
  • library/functions.html
  • library/inspect.html
  • and 6 more...
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@encukou encukou added the sprint label Jul 18, 2026
@github-project-automation github-project-automation Bot added this to Sprint Jul 18, 2026
@github-project-automation github-project-automation Bot moved this to Todo in Sprint Jul 18, 2026
@encukou encukou self-assigned this Jul 18, 2026
encukou
encukou reviewed Jul 18, 2026
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Comment thread Doc/library/difflib.rst Resolved

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Comment thread Doc/library/difflib.rst Resolved

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Comment thread Doc/library/difflib.rst Resolved

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This was referenced Jul 18, 2026
gh-118150: expose autojunk SequenceMathcher flag to public methods/functions of difflib #153947
Closed
gh-118150: difflib: expose autojunk flag from SequenceMatcher to public methods and functions #153959
Merged
Lenormju added 3 commits July 18, 2026 17:13
@Lenormju
merge and reword the whole junk mechanism
39e47c3
@Lenormju
remove all notes, keep only junk explanation at the top
1d9605e
@Lenormju
update NEWS to the current content of the PR
0793740
encukou
encukou reviewed Jul 19, 2026
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Comment thread Doc/library/difflib.rst
Comment on lines 22 to 25
.. class:: SequenceMatcher
:noindex:

This is a flexible class for comparing pairs of sequences of any type, so long

@encukou encukou Jul 19, 2026

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What do you think about making this an introduction to the difflib module, rather than docs for the SequenceMatcher class (which is documented properly below)?

Something like this, plus dedenting it:

All functionality in this module uses the algorithm implemented in
:class:`SequenceMatcher`, a flexible class for comparing pairs
of sequences of any type, so long […]

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@Lenormju Lenormju Jul 20, 2026

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I agree, because in the end everything relies on it. But can we do that in another PR, iteratively ?

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@encukou encukou Jul 24, 2026

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OK. I'll send the PR.

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@encukou encukou Jul 24, 2026

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Sent: #154662

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@encukou encukou added needs backport to 3.13 only security fixes needs backport to 3.14 bugs and security fixes needs backport to 3.15 bugs and security fixes labels Jul 24, 2026
@encukou
encukou merged commit 59e67c2 into python:main Jul 24, 2026
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@github-project-automation github-project-automation Bot moved this from Todo to Done in Docs PRs Jul 24, 2026
@github-project-automation github-project-automation Bot moved this from Todo to Done in Sprint Jul 24, 2026
@miss-islington-app

miss-islington-app Bot commented Jul 24, 2026

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Thanks @Lenormju for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15.
🐍🍒⛏🤖
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@bedevere-app bedevere-app Bot removed the awaiting review label Jul 24, 2026
@bedevere-app

bedevere-app Bot commented Jul 24, 2026

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GH-154658 is a backport of this pull request to the 3.15 branch.
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@bedevere-app bedevere-app Bot removed the needs backport to 3.15 bugs and security fixes label Jul 24, 2026
@bedevere-app

bedevere-app Bot commented Jul 24, 2026

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GH-154659 is a backport of this pull request to the 3.14 branch.
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@bedevere-app bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Jul 24, 2026
@bedevere-app

bedevere-app Bot commented Jul 24, 2026

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GH-154660 is a backport of this pull request to the 3.13 branch.
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@bedevere-app bedevere-app Bot removed the needs backport to 3.13 only security fixes label Jul 24, 2026
encukou pushed a commit that referenced this pull request Jul 24, 2026
@miss-islington @Lenormju
[3.15] gh-118150: warn in doc about results asymmetry for difflib junk (
1f53f91 
GH-153892) (GH-154658)

(cherry picked from commit 59e67c2)

Co-authored-by: Lenormand Julien <[email protected]>
encukou pushed a commit that referenced this pull request Jul 24, 2026
@miss-islington @Lenormju
[3.14] gh-118150: warn in doc about results asymmetry for difflib junk (
a73668a 
GH-153892) (GH-154659)

(cherry picked from commit 59e67c2)

Co-authored-by: Lenormand Julien <[email protected]>
encukou pushed a commit that referenced this pull request Jul 24, 2026
@miss-islington @Lenormju
[3.13] gh-118150: warn in doc about results asymmetry for difflib junk (
970a738 
GH-153892) (GH-154660)

(cherry picked from commit 59e67c2)

Co-authored-by: Lenormand Julien <[email protected]>
@Lenormju
Lenormju deleted the gh-118150-difflib-autojunk-asymmetry-doc branch August 11, 2026 11:04
mbeijen pushed a commit to mbeijen/cpython that referenced this pull request Aug 14, 2026
@Lenormju @mbeijen
pythongh-118150: warn in doc about results asymmetry for difflib junk (…
d0efede 
…pythonGH-153892)
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@Lenormju @encukou
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