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Context management support for subprocess.Popen #54763

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merwok opened this issue Nov 27, 2010 · 8 comments
Closed

Context management support for subprocess.Popen #54763

merwok opened this issue Nov 27, 2010 · 8 comments
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@briancurtin
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easy stdlib Python modules in the Lib dir type-feature A feature request or enhancement

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@merwok
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merwok commented Nov 27, 2010

BPO 10554
Nosy @merwok, @briancurtin
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  • subprocess.diff
  • subprocess2.diff
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = 'https://github.com/briancurtin'
closed_at = <Date 2010-12-03.02:50:33.187>
created_at = <Date 2010-11-27.20:47:38.378>
labels = ['easy', 'type-feature', 'library']
title = 'Context management support for subprocess.Popen'
updated_at = <Date 2010-12-03.02:50:33.186>
user = 'https://github.com/merwok'

    bugs.python.org fields:

    activity = <Date 2010-12-03.02:50:33.186>
actor = 'eric.araujo'
assignee = 'brian.curtin'
closed = True
closed_date = <Date 2010-12-03.02:50:33.187>
closer = 'eric.araujo'
components = ['Library (Lib)']
creation = <Date 2010-11-27.20:47:38.378>
creator = 'eric.araujo'
dependencies = []
files = ['19916', '19917']
hgrepos = []
issue_num = 10554
keywords = ['patch', 'easy']
message_count = 8.0
messages = ['122554', '123155', '123156', '123159', '123160', '123161', '123164', '123165']
nosy_count = 2.0
nosy_names = ['eric.araujo', 'brian.curtin']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue10554'
versions = ['Python 3.2']
    @merwok
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    merwok commented Nov 27, 2010

    I propose that __enter__ and __exit__ be added to subprocess.Popen. __enter__ returns self, __exit__ closes open file descriptors.

    __exit__ could also do the same checks that __del__ does (and which I don’t entirely understand.

    See also os.popen (os._wrap_close).

    @merwok merwok added stdlib Python modules in the Lib dir easy type-feature A feature request or enhancement labels Nov 27, 2010
    @briancurtin
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    Here's a patch which implements the context manager and adds a few tests and a small doc change.

    Tested on Mac and Windows.

    @merwok
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    merwok commented Dec 3, 2010

    Thanks! Patch looks good, tests pass and doc builds.

    I have one question and two micro-nitpicks on http://codereview.appspot.com/3441041/

    @briancurtin
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    I updated the doc to be much more simple. I got used to sys.executable based tests :) New patch attached.

    As for __del__, I think it should do it's thing, and the exit will do it's own. Context managers are traditionally used on file-based things, or things that can be opened or closed. Creating a Popen object will open one or more pipes, so we should just close those opened pipes.

    @merwok
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    merwok commented Dec 3, 2010

    New doc looks good. Suggested changes: make with a link, explaing why it’s a context manager.

    • Popen objects are supported as context managers via the ``with`` statement.
      + Popen objects are supported as context managers via the :keyword:`with`` statement, so that file descriptors are closed cleanly.

    I agree with your view on __del__ vs. __exit__.

    @merwok
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    merwok commented Dec 3, 2010

    :keyword:`with`` → :keyword:`with`

    @abalkin abalkin changed the title Context managerment support for subprocess.Popen Context management support for subprocess.Popen Dec 3, 2010
    @briancurtin
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    Committed in r86951. Thanks for the reviews!

    @briancurtin briancurtin self-assigned this Dec 3, 2010
    @merwok
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    merwok commented Dec 3, 2010

    “closing any open file descriptors on exit” is exactly the perfect wording I was looking for. Thanks for the patch!

    @merwok merwok closed this as completed Dec 3, 2010
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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