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GeezerVison is showing github.com — bpo-25625: add contextlib.chdir by FFY00 · Pull Request #28271 · python/cpython

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@FFY00

@FFY00 FFY00 commented Sep 10, 2021 •
edited by bedevere-bot
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This is probably the single snippet of code I find myself re-implementing the
most in projects. Not being thread safe is not optimal, but there isn't
really any good way to do so, and that does not negate the huge
usefulness of this function.

Signed-off-by: Filipe Laíns [email protected]

https://bugs.python.org/issue25625

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@FFY00
FFY00 requested a review from 1st1 as a code owner September 10, 2021 14:33
@the-knights-who-say-ni the-knights-who-say-ni added the CLA signed label Sep 10, 2021
@bedevere-bot bedevere-bot added the awaiting review label Sep 10, 2021
@FFY00
bpo-25625: add contextlib.chdir
1d1f1e8 
This is probably the single snippet of code I find myself re-implementing the
most in projects. Not being thread safe is not optimal, but there isn't
really any good way to do so, and that does not negate the huge
usefulness of this function.

Signed-off-by: Filipe Laíns <[email protected]>
@FFY00
FFY00 force-pushed the bpo-25625 branch from da4b329 to 1d1f1e8 Compare September 10, 2021 14:52
kalvdans
kalvdans reviewed Sep 10, 2021
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Comment thread Lib/test/test_contextlib.py Resolved

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ambv
ambv reviewed Sep 10, 2021
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Comment thread Lib/test/test_contextlib.py Resolved

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@ambv
Ensure own exception
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ambv
ambv reviewed Sep 10, 2021
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Comment thread Doc/library/contextlib.rst Resolved

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@ambv
Use Oxford comma
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kalvdans
kalvdans reviewed Sep 10, 2021
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Comment thread Lib/test/test_contextlib.py Resolved

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FFY00
FFY00 commented Sep 10, 2021
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@ambv @FFY00
Update Lib/test/test_contextlib.py
6bdf5bb 
Co-authored-by: Filipe Laíns <[email protected]>
serhiy-storchaka
serhiy-storchaka reviewed Sep 15, 2021
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Comment thread Doc/library/contextlib.rst Resolved

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@FFY00
Serhiy's feedback
e30c9d8 
Signed-off-by: Filipe Laíns <[email protected]>
tiran
tiran reviewed Sep 15, 2021
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I'm -1 to add this feature.

The presence of a chdir decorator in Python's stdlib promotes the idea that the feature is a good standard practice. However it is ill-advised to change process global state such as the working directory in most cases.

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@tiran tiran mentioned this pull request Sep 15, 2021
Please decide on chdir() / workdir() context manager python/steering-council#77
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serhiy-storchaka
serhiy-storchaka reviewed Sep 15, 2021
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Technically it looks correct to me. I am not sure that such feature should be added, although the can of worms was opened by redirect_stdout().

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@warsaw

warsaw commented Sep 16, 2021

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I agree with the comment that it can be problematic, but OTOH it's very common to reimplement this code over and over. There's something to be said for providing a solid reference implementation that at least does the best you can do, but with big red warnings for when it can go wrong. Not having this in the stdlib isn't going to stop people from doing it anyway.
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@ambv

ambv commented Sep 17, 2021

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The presence of a chdir decorator in Python's stdlib promotes the idea that the feature is a good standard practice. However it is ill-advised to change process global state such as the working directory in most cases.

I disagree. os.chdir exists since forever, it "promotes" the idea the same way as a context manager would. If anything, the context manager is a better way to do it, since it will at least return to the previous state.

Sure, any global modifications of the environment are potential anti-patterns, like monkey-patching standard input/output that Serhiy already mentioned (see BPO-30511 for an egregious example why that is a problem).

That being said, again, os.chdir() is a popular facility of the language, used in our unit tests many times. Using a context manager for it would make more sense. In fact, we already do support that.
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@ambv
Merge main to work around BPO-45220 unrelated Windows failures
0cb2d8b
@1st1

1st1 commented Sep 17, 2021

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I'm really not sure this should be part of contextlib (or the stdlib). I'd just add this as a recipe to the docs.
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FFY00 added 2 commits September 18, 2021 18:39
@FFY00
refeer that the cm is not parallel-safe in the news entry
9ad9398 
Signed-off-by: Filipe Laíns <[email protected]>
@FFY00
fix typo in news
ce10241 
Signed-off-by: Filipe Laíns <[email protected]>
@FFY00

FFY00 commented Oct 18, 2021

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Per python/steering-council#77, it seems that addition of such a context manager was approved, granted that we have an appropriate warning.
I think the current warning is good enough, does anyone have suggestions?

Otherwise, this PR is now unblocked 🙂
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warsaw
warsaw reviewed Oct 18, 2021
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@ambv
ambv merged commit 3592980 into python:main Oct 19, 2021
@bedevere-bot bedevere-bot removed the awaiting review label Oct 19, 2021
graingert
graingert reviewed Oct 20, 2021
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Comment thread Doc/library/contextlib.rst

Non parallel-safe context manager to change the current working directory.
As this changes a global state, the working directory, it is not suitable
for use in most threaded or aync contexts. It is also not suitable for most

@graingert graingert Oct 20, 2021

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typo on aync #29091

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@graingert graingert mentioned this pull request Oct 23, 2021
add contextlib.chdir python/typeshed#6191
Merged
jcfr added a commit to jcfr/Slicer that referenced this pull request Apr 29, 2022
@jcfr
ENH: Add slicer.util.chdir context manager
13dfeb2 
This commit implements a non thread-safe context manager to change
the current working directory.

Available in Python 3.11 as ``contextlib.chdir`` and adapted from
python/cpython#28271.
@jcfr jcfr mentioned this pull request Apr 29, 2022
ENH: Add slicer.util.chdir context manager Slicer/Slicer#6341
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jcfr added a commit to Slicer/Slicer that referenced this pull request Apr 29, 2022
@jcfr
ENH: Add slicer.util.chdir context manager
5cab260 
This commit implements a non thread-safe context manager to change
the current working directory.

Available in Python 3.11 as ``contextlib.chdir`` and adapted from
python/cpython#28271.
@AlexGaynor AlexGaynor mannequin mentioned this pull request Apr 10, 2022
shutil.make_archive should not need to chdir (alternatively: make shutil.make_archive thread-safe) #74696
Closed
@hamelsmu hamelsmu mentioned this pull request Jul 18, 2022
add context manager for changing directories AnswerDotAI/fastcore#436
Closed
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@ambv ambv ambv left review comments
@warsaw warsaw warsaw left review comments
@graingert graingert graingert left review comments
@serhiy-storchaka serhiy-storchaka serhiy-storchaka left review comments
@1st1 1st1 Awaiting requested review from 1st1
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10 participants

@FFY00 @warsaw @ambv @1st1 @graingert @tiran @kalvdans @serhiy-storchaka @the-knights-who-say-ni @bedevere-bot
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