bpo-44986: Fixed bug with date formats like %Y-%m-%d in help messages of argparse #27923

SengerM · 2021-08-23T23:26:16Z

Fixed bug with date formats like %Y-%m-%d in help messages of argparse

Now this code does not produce any error when invoked with the -h option and produces the expected result:

import argparse

parser = argparse.ArgumentParser(description = 'Just a test code.')
parser.add_argument(
	'--from',
	metavar = 'when', 
	help = 	'A date in format %Y-%m-%d',
	dest = f'From',
	type = str,
	required = True,
)
args = parser.parse_args()

print(args.From)

https://bugs.python.org/issue44986

…}' formatting

the-knights-who-say-ni · 2021-08-23T23:26:19Z

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SengerM · 2021-08-24T19:13:27Z

I don't know if a human will ever read this, but if so I have already signed the CLA yesterday and in the check yourself page still says that I have not signed it. Is it normal that it takes so long?

Lib/test/test_argparse.py

…lace escaped %% in the expand help method

github-actions · 2021-10-01T00:05:46Z

This PR is stale because it has been open for 30 days with no activity.

MaxwellDupre

Ran the argparse test module:
Ran 1670 tests in 3.185s
OK
== Tests result: SUCCESS ==

And example in bug ok.

furkanonder · 2023-05-09T11:46:44Z

@SengerM Can you add the unit tests for this case?

bedevere-bot · 2023-08-22T16:38:38Z

Most changes to Python require a NEWS entry.

Please add it using the blurb_it web app or the blurb command-line tool.

…to escape `%` in help messages of `argparse`

bedevere-bot · 2023-08-22T22:57:21Z

Most changes to Python require a NEWS entry.

Please add it using the blurb_it web app or the blurb command-line tool.

SengerM · 2023-08-23T08:38:32Z

Dear @furkanonder , sorry for the long delay. I added the test case. I see there are fails in the tests for macOS, but they don't seem related to my changes.

savannahostrowski

I know this PR has been sitting for a little while, but I pulled it down and rebased it with the main, and it still resolves the bug. Just a couple of comments but overall, this LGTM.

savannahostrowski · 2024-09-23T01:32:53Z

Lib/argparse.py

-        return self._get_help_string(action) % params
+        expanded_help = self._get_help_string(action)
+        for param, value in params.items():
+            if f'%({param})s' in expanded_help:


I think this conditional is redundant, right? Doesn't replace() handle validating that the string is contained by expanded_help?

savannahostrowski · 2024-09-23T01:34:14Z

Lib/test/test_argparse.py

    version = ''

+class TestHelpWithPercentageSymbols(HelpTestCase):
+    """Test a help message including % symbols"""


Suggested change

"""Test a help message including % symbols"""

"""Test help output that includes % symbols"""

savannahostrowski · 2024-09-23T01:34:24Z

Lib/test/test_argparse.py


+class TestHelpWithPercentageSymbols(HelpTestCase):
+    """Test a help message including % symbols"""
+    parser_signature = Sig(prog='PROG', description='Just a test code.')


Suggested change

parser_signature = Sig(prog='PROG', description='Just a test code.')

parser_signature = Sig(prog='PROG', description='Just a test program.')

savannahostrowski · 2024-09-23T01:35:13Z

Lib/test/test_argparse.py

+    parser_signature = Sig(prog='PROG', description='Just a test code.')
+    argument_signatures = [
+        Sig('--somearg', metavar='somearg',
+            help='Now you dont need to escape this: %, and you will not get nonsensical errors!'),


Suggested change

help='Now you dont need to escape this: %, and you will not get nonsensical errors!'),

help='No escape required for %'),

savannahostrowski · 2024-09-23T01:35:47Z

Lib/test/test_argparse.py

+    argument_signatures = [
+        Sig('--somearg', metavar='somearg',
+            help='Now you dont need to escape this: %, and you will not get nonsensical errors!'),
+        Sig('--date', metavar='when',  help='A date in format %Y-%m-%d',


Suggested change

Sig('--date', metavar='when', help='A date in format %Y-%m-%d',

Sig('--date', metavar='when', help='A date in %Y-%m-%d format',

savannahostrowski · 2024-09-23T01:36:54Z

Lib/test/test_argparse.py

+        Sig('--date', metavar='when',  help='A date in format %Y-%m-%d',
+            dest=f'date', type=str, required=True),
+        Sig('bar', nargs='?', type=int, default=42,
+            help='the bar to %(prog)s (default: %(default)s)'),


Suggested change

help='the bar to %(prog)s (default: %(default)s)'),

help='The bar to %(prog)s (default: %(default)s)'),

serhiy-storchaka

It's not that simple.

What if the replacement value contains %% or %(prog)s? Or only the part of it, and the other part is contained in the help string? E.g. help='%(default)s(prog)s', where default='%'.

What if the help string contains %(...)r or %(...)a instead of %(...)s?

bedevere-app · 2024-09-24T10:24:33Z

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

serhiy-storchaka · 2024-10-12T10:22:35Z

argparse now checks help string for correctness, so you will be informed about errors earlier.

You can implement a "safe" help formatter as a separate class, but this is not easy task. I am not sure that argparse needs this. It is easier to fix help strings in the user code.

Updated the usage of the '%(par)s' string formatting to modern f'{par…

04f909d

…}' formatting

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rhettinger reviewed Aug 24, 2021

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bpo-44986: Reverted change in test to stick to the old format and rep…

36001c7

…lace escaped %% in the expand help method

the-knights-who-say-ni added CLA signed and removed CLA not signed labels Aug 31, 2021

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MaxwellDupre approved these changes Mar 9, 2022

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SengerM mannequin mentioned this pull request Apr 10, 2022

Date formats in help messages of argparse #89149

Closed

ezio-melotti removed the CLA signed label Jul 13, 2022

github-actions bot removed the stale Stale PR or inactive for long period of time. label Aug 12, 2022

Merge branch 'main' into main

d77b2b6

SengerM added 2 commits August 23, 2023 00:47

bpo-44986: Added unit tests for new feature that eliminates the need …

255fa92

…to escape `%` in help messages of `argparse`

bpo-44986: Added one extra test case with multiple percentage symbols

cbdc58e

SengerM added 5 commits August 23, 2023 01:11

bpo-44986: Added blurb entry

f291df2

bpo-44986: Removed trailing white spaces

8ed8045

Merge branch 'main' into main

cd7aebb

Fixed GitHub issue number

1728042

Merge branch 'main' into main

8697b09

SengerM requested a review from rhettinger August 23, 2023 08:43

rhettinger removed their request for review August 23, 2023 23:16

furkanonder and others added 2 commits September 29, 2023 02:00

Merge branch 'main' into main

a3be094

Merge branch 'main' into main

02e3b73

savannahostrowski requested changes Sep 23, 2024

View reviewed changes

Merge branch 'main' into main

60c3e50

serhiy-storchaka requested changes Sep 24, 2024

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bedevere-app bot added awaiting changes and removed awaiting core review labels Sep 24, 2024

serhiy-storchaka closed this Oct 12, 2024

	"""Test a help message including % symbols"""
	"""Test help output that includes % symbols"""

	parser_signature = Sig(prog='PROG', description='Just a test code.')
	parser_signature = Sig(prog='PROG', description='Just a test program.')

	help='Now you dont need to escape this: %, and you will not get nonsensical errors!'),
	help='No escape required for %'),

	Sig('--date', metavar='when', help='A date in format %Y-%m-%d',
	Sig('--date', metavar='when', help='A date in %Y-%m-%d format',

	help='the bar to %(prog)s (default: %(default)s)'),
	help='The bar to %(prog)s (default: %(default)s)'),

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bpo-44986: Fixed bug with date formats like %Y-%m-%d in help messages of argparse #27923

bpo-44986: Fixed bug with date formats like %Y-%m-%d in help messages of argparse #27923

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Fixed bug with date formats like %Y-%m-%d in help messages of argparse

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the-knights-who-say-ni commented Aug 23, 2021

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SengerM commented Aug 23, 2021 •

edited by bedevere-bot

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