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GeezerVison is showing github.com — GH-54732: Tweak wording around empty lines in argument files by savannahostrowski · Pull Request #150980 · python/cpython

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@savannahostrowski

@savannahostrowski savannahostrowski commented Jun 5, 2026 •
edited by bedevere-app Bot
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Follow-up to #136795.

Revises the empty-lines note to address the concerns raised in #54732 (comment), and adds a caveat to the convert_arg_line_to_args example that split-based parsing can't represent arguments containing spaces.

  • Issue: argparse has problem parsing option files containing empty rows #54732

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@savannahostrowski
Tweak wording around empty lines in argument files
8bc2d08
@savannahostrowski savannahostrowski added docs Documentation in the Doc dir 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 Jun 5, 2026
@github-project-automation github-project-automation Bot added this to Docs PRs Jun 5, 2026
@github-project-automation github-project-automation Bot moved this to Todo in Docs PRs Jun 5, 2026
@bedevere-app bedevere-app Bot added awaiting core review skip news labels Jun 5, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Jun 5, 2026
argparse has problem parsing option files containing empty rows #54732
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@savannahostrowski savannahostrowski linked an issue Jun 5, 2026 that may be closed by this pull request
argparse has problem parsing option files containing empty rows #54732
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@savannahostrowski
Merge branch 'main' into pythongh-54732-fromfile-empty-line-doc
08fe6b9
@read-the-docs-community

read-the-docs-community Bot commented Jun 5, 2026 •
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Documentation build overview

📚 cpython-previews | 🛠️ Build #33060979 | 📁 Comparing 0f80836 against main (6544bf4)

  🔍 Preview build  

17 files changed · ± 17 modified

± Modified

  • c-api/long.html
  • c-api/typeobj.html
  • howto/functional.html
  • library/argparse.html
  • library/bisect.html
  • library/collections.abc.html
  • library/collections.html
  • library/importlib.resources.html
  • library/logging.handlers.html
  • library/math.html
  • and 7 more...
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clytaemnestra
clytaemnestra reviewed Jun 9, 2026
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Comment thread Doc/library/argparse.rst
Comment on lines +445 to +446
Each line is treated as a single argument, so an empty line is read as an
empty string (``''``).

@clytaemnestra clytaemnestra Jun 9, 2026

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I tried to simulate the situation where empty strings are passed from a file and it doesn't return an unrecognized argument, so this note makes much more sense to me and is perfectly understandable.

I also tried to simulate the unrecognized arguments error to see when it appears and my understanding is that it's related to leftover tokens in general rather than empty strings. So, if my understanding is correct, it also makes sense that it was removed here.

So, overall, the new wording is much clearer to me.

>>> import argparse
>>> with open("args.txt", "w") as f:
...   f.write("-f\n\nbar\n")
...
8
>>> parser = argparse.ArgumentParser(fromfile_prefix_chars="@")
>>> parser.add_argument("-f")
_StoreAction(option_strings=['-f'], dest='f', nargs=None, const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None, deprecated=False)
>>> parser.add_argument("rest", nargs="*")
_StoreAction(option_strings=[], dest='rest', nargs='*', const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None, deprecated=False)
>>> parser._read_args_from_files(["@args.txt"])
['-f', '', 'bar']
>>> parser.parse_args(["@args.txt"])
Namespace(f='', rest=['bar'])
>>> p2 = argparse.ArgumentParser(fromfile_prefix_chars="@")
>>> p2.add_argument("-f")
_StoreAction(option_strings=['-f'], dest='f', nargs=None, const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None, deprecated=False)
>>> p2.parse_args(["@args.txt"])
usage: [-h] [-f F]
: error: unrecognized arguments: bar

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@savannahostrowski
Merge branch 'main' into pythongh-54732-fromfile-empty-line-doc
0f80836
@savannahostrowski
savannahostrowski enabled auto-merge (squash) June 9, 2026 15:28
@savannahostrowski
savannahostrowski merged commit 528550e into python:main Jun 9, 2026
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@github-project-automation github-project-automation Bot moved this from Todo to Done in Docs PRs Jun 9, 2026
@miss-islington-app

miss-islington-app Bot commented Jun 9, 2026

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Thanks @savannahostrowski for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15.
🐍🍒⛏🤖
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@bedevere-app

bedevere-app Bot commented Jun 9, 2026

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GH-151165 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 Jun 9, 2026
@bedevere-app

bedevere-app Bot commented Jun 9, 2026

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GH-151166 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 Jun 9, 2026
@bedevere-app

bedevere-app Bot commented Jun 9, 2026

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GH-151167 is a backport of this pull request to the 3.13 branch.
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@bedevere-app bedevere-app Bot removed needs backport to 3.13 only security fixes awaiting core review labels Jun 9, 2026
savannahostrowski added a commit that referenced this pull request Jun 9, 2026
@miss-islington @savannahostrowski
[3.13] GH-54732: Tweak wording around empty lines in argument files (G…
b032f3f 
…H-150980) (#151167)

GH-54732: Tweak wording around empty lines in argument files (GH-150980)
(cherry picked from commit 528550e)

Co-authored-by: Savannah Ostrowski <[email protected]>
savannahostrowski added a commit that referenced this pull request Jun 9, 2026
@miss-islington @savannahostrowski
[3.14] GH-54732: Tweak wording around empty lines in argument files (G…
9d92876 
…H-150980) (#151166)

GH-54732: Tweak wording around empty lines in argument files (GH-150980)
(cherry picked from commit 528550e)

Co-authored-by: Savannah Ostrowski <[email protected]>
savannahostrowski added a commit that referenced this pull request Jun 9, 2026
@miss-islington @savannahostrowski
[3.15] GH-54732: Tweak wording around empty lines in argument files (G…
804be0a 
…H-150980) (#151165)

GH-54732: Tweak wording around empty lines in argument files (GH-150980)
(cherry picked from commit 528550e)

Co-authored-by: Savannah Ostrowski <[email protected]>
clin1234 pushed a commit to clin1234/cpython that referenced this pull request Jun 9, 2026
@savannahostrowski unknown
pythonGH-54732: Tweak wording around empty lines in argument files (p…
1bfa4fd 
…ython#150980)
philthompson10 pushed a commit to philthompson10/cpython that referenced this pull request Jun 17, 2026
@savannahostrowski @philthompson10
pythonGH-54732: Tweak wording around empty lines in argument files (p…
bd81be7 
…ython#150980)
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argparse has problem parsing option files containing empty rows

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@savannahostrowski @clytaemnestra
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