Opaque default value for close_fds argument in Popen.__init__

[ghost]

BPO	31823
Nosy	@gpshead, @taleinat, @vadmium, @danishprakash
PRs	bpo-31823 - subprocess.rst: remove outdated changes #11039

^{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 = None
closed_at = <Date 2018-12-10.17:38:08.992>
created_at = <Date 2017-10-19.20:34:16.384>
labels = ['easy', '3.7', '3.8', 'docs']
title = 'Opaque default value for close_fds argument in Popen.__init__'
updated_at = <Date 2018-12-13.08:13:06.116>
user = None

bugs.python.org fields:

activity = <Date 2018-12-13.08:13:06.116>
actor = 'martin.panter'
assignee = 'docs@python'
closed = True
closed_date = <Date 2018-12-10.17:38:08.992>
closer = 'gregory.p.smith'
components = ['Documentation']
creation = <Date 2017-10-19.20:34:16.384>
creator = '\xd0\x90\xd0\xbb\xd0\xb5\xd0\xba\xd1\x81\xd0\xb5\xd0\xb9 \xd0\x90\xd0\xb2\xd0\xb5\xd1\x80\xd1\x87\xd0\xb5\xd0\xbd\xd0\xba\xd0\xbe'
dependencies = []
files = []
hgrepos = []
issue_num = 31823
keywords = ['patch', 'easy']
message_count = 9.0
messages = ['304642', '314413', '322354', '330297', '330298', '331527', '331680', '331721', '331747']
nosy_count = 6.0
nosy_names = ['gregory.p.smith', 'taleinat', 'docs@python', 'martin.panter', '\xd0\x90\xd0\xbb\xd0\xb5\xd0\xba\xd1\x81\xd0\xb5\xd0\xb9 \xd0\x90\xd0\xb2\xd0\xb5\xd1\x80\xd1\x87\xd0\xb5\xd0\xbd\xd0\xba\xd0\xbe', 'danishprakash']
pr_nums = ['11039']
priority = 'normal'
resolution = 'wont fix'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue31823'
versions = ['Python 3.7', 'Python 3.8']

[ghost]

[11:30:03 ~]$ python
Python 3.6.1 |Anaconda 4.4.0 (x86_64)| (default, May 11 2017, 13:04:09)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import subprocess
>>> help(subprocess.Popen.__init__)
Help on function __init__ in module subprocess:

__init__(self, args, bufsize=-1, executable=None, stdin=None, stdout=None, stderr=None, preexec_fn=None, close_fds=<object object at 0x10df99150>, shell=False, cwd=None, env=None, universal_newlines=False, startupinfo=None, creationflags=0, restore_signals=True, start_new_session=False, pass_fds=(), *, encoding=None, errors=None)
Create new Popen instance.

[vadmium]

The close_fds=<object . . .> in that signature seems fine to me. If you read the documentation, it says the default mode depends on the platform, and on other parameters. However I think the signature at <https://docs.python.org/release/3.6.4/library/subprocess.html#subprocess.Popen\> should not show close_fds=True, because that is not necessarily the default on Windows.

It seems the default on Windows was changed to always True in 3.7, making it consistent across platforms and other parameters, thanks to bpo-19764. But the 3.7 documentation is quirky. “Changed in version 3.2: The default for ‘close_fds’ was changed from False to what is described above” refers to the 3.7 default when it was meant to refer to the 3.2–3.6 default.

[taleinat]

ISTM that the docs need to be fixed for both 3.7+ and for 3.6.

The signature is indeed awkward for 3.6, but it's too minor a detail to address considering it's no longer relevant for 3.7 and later.

[danishprakash]

I'd like to work on this.

I get that the 3.7+ doc still has the irrelevant change from 3.6 which needs to be removed but I'm not sure what's wrong with the 3.6 doc.

The signature is indeed awkward for 3.6,

[taleinat]

Danish, see Martin's previous comment (msg314413):

"... the signature at [the 3.6 docs] should not show close_fds=True, because that is not necessarily the default on Windows."

[gpshead]

In 3.6 this help(subprocess.Popen.__init__) is accurate and encourages looking at the docs. In 3.7 and later it'll simply report close_fds=True in the siguature as that is the case in 3.7 onwards.

I see nothing to fix here.

[taleinat]

Gregory, this issue was about the docs, not the doc-string (help()). Are you sure it should be closed?