gh-74185: repr() of ImportError now contains attributes name and path by Yoav11 · Pull Request #136770 · python/cpython · GitHub

This PR was created during Europython 2025's sprint weekend.

This is a patch on #1011. authored by serhiy-storchaka and arhadthedev

Issue: repr() of ImportError misses keyword arguments name and path #74185

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Requesting @encukou who wanted to finish this per #1011 (comment)

This looks good now. I'll let @serhiy-storchaka have a look as well.

thanks for the review @picnixz ! 🙏

LGTM!

I plan to merge this around Wednesday if there are no objections.

Sorry for ignoring this PR earlier. It did not looked important to me, and I was no longer sure about its usefulness, because path is usually so long.

Why use PyUnicodeWriter at first place? Does it make the code smaller/clearer? Is the performance difference too large?

Sorry for ignoring this PR earlier. It did not looked important to me, and I was no longer sure about its usefulness, because path is usually so long.

Why use PyUnicodeWriter at first place? Does it make the code smaller/clearer? Is the performance difference too large?

@picnixz recommended PyUnicodeWriter in #136770 (comment)

What were the problems with recreating the strings? Do you have any benchmark data?

@serhiy-storchaka, what would be your preferred alternative to PyUnicodeWriter? As far as I know, @vstinner added it exactly for use cases like this.

The original PR used PyUnicode_Substring() and PyUnicode_FromFormat() (similar code is also used in other places). It was pretty compact, half as short as the current code in this PR. It had also fast path for the case without keyword argument. I ask what are the benefits of the larger code. Is it performance? I would like to see the data.

LGTM.

I'm fine with PyUnicodeWriter usage in this PR. It makes the code more verbose (than the first PR version), but the code is easy to read.

The original PR used PyUnicode_Substring() and PyUnicode_FromFormat() (similar code is also used in other places). It was pretty compact, half as short as the current code in this PR. It had also fast path for the case without keyword argument. I ask what are the benefits of the larger code. Is it performance? I would like to see the data.

@serhiy-storchaka Please see a small benchmark test of the two alternatives here Yoav11#1
at least from this naive test it would appear to me that the PyUnicdeWriter implementation is ~25% faster. Lmk if you would like me to change the benchmark / try a different test case

The code is bigger because it uses an extra function call rather than %s with hasargs ? ", " : "". It would be possible to do that with PyUnicodeWriter_Format too, and get back to roughly the same size of code.
I personally find the if (hasargs) {PyUnicodeWriter_WriteASCII(...)} more readable.

Thank you for your benchmark, @Yoav11. I checked myself, indeed, there is a measurable difference.

LGTM. 👍

Merged, thanks.

thank you @vstinner @serhiy-storchaka @encukou @StanFromIreland @picnixz ! 🚀 🐍

…d path (python#136770) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Oleg Iarygin <oleg@arhadthedev.net> Co-authored-by: ynir3 <ynir3@bloomberg.net>

serhiy-storchaka and others added 5 commits July 19, 2025 09:43

bpo-29999: repr() of ImportError now contains attributes name and path.

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bedevere-app Bot mentioned this pull request Jul 19, 2025

repr() of ImportError misses keyword arguments name and path #74185

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Yoav11 changed the title gh-74185: (patch) repr() of ImportError now contains attributes name and path. gh-74185: repr() of ImportError now contains attributes name and path. (patch) Jul 19, 2025

ynir3 added 2 commits July 19, 2025 10:23

add test_ModuleNotFoundError_repr_with_failed_import

126be20

add test_ModuleNotFoundError_repr_with_failed_import

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StanFromIreland requested review from encukou and serhiy-storchaka July 19, 2025 08:28

ynir3 added 6 commits July 19, 2025 10:36

add blurb

852da8c

add noqa:F401

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remove whitespace

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fix trailing-whitespace

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use ComplexExtendsException

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return to non-macro style

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picnixz reviewed Jul 19, 2025

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Comment thread Objects/exceptions.c Outdated

use modern field initializers

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picnixz reviewed Jul 19, 2025

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Comment thread Objects/exceptions.c Outdated

picnixz reviewed Jul 19, 2025

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Comment thread Objects/exceptions.c Outdated

remove un-necessary casts

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picnixz changed the title gh-74185: repr() of ImportError now contains attributes name and path. (patch) gh-74185: repr() of ImportError now contains attributes name and path Jul 19, 2025

ynir3 added 3 commits July 19, 2025 12:52

use PyUnicodeWriter

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fix trailing whitespace

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reduce nesting

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edit blurb

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edit blurb

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AA-Turner added the sprint label Jul 20, 2025

brettcannon added the topic-importlib label Jul 22, 2025

Merge branch 'main' into importerror-repr

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encukou approved these changes Aug 11, 2025

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bedevere-app Bot added awaiting merge and removed awaiting review labels Aug 11, 2025

webknjaz reviewed Aug 12, 2025

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Comment thread Doc/whatsnew/3.15.rst

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serhiy-storchaka reviewed Aug 13, 2025

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serhiy-storchaka removed the DO-NOT-MERGE label Aug 13, 2025

Merge branch 'main' into importerror-repr

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vstinner approved these changes Aug 13, 2025

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Yoav11 requested a review from AA-Turner as a code owner August 13, 2025 12:06

Yoav11 mentioned this pull request Aug 13, 2025

Benchmark ImportError_repr Yoav11/cpython#1

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Py_DECREF and early exit logic

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serhiy-storchaka approved these changes Aug 14, 2025

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vstinner merged commit c87b66b into python:main Aug 14, 2025

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gh-74185: repr() of ImportError now contains attributes name and path by Yoav11 · Pull Request #136770 · python/cpython · GitHub

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gh-74185: repr() of ImportError now contains attributes name and path - #136770

gh-74185: repr() of ImportError now contains attributes name and path#136770vstinner merged 31 commits intopython:mainpython/cpython:mainfrom Yoav11:importerror-reprYoav11/cpython:importerror-reprCopy head branch name to clipboard

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gh-74185: repr() of ImportError now contains attributes name and path#136770
vstinner merged 31 commits into
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Yoav11:importerror-repr

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