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Document that ctypes.xFUNCTYPE are decorators. #48510

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lambertdw mannequin opened this issue Nov 5, 2008 · 8 comments
Closed

Document that ctypes.xFUNCTYPE are decorators. #48510

lambertdw mannequin opened this issue Nov 5, 2008 · 8 comments
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3.7 (EOL) end of life 3.8 only security fixes docs Documentation in the Doc dir easy type-feature A feature request or enhancement

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@lambertdw
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Mannequin

lambertdw mannequin commented Nov 5, 2008

BPO 4260
Nosy @theller, @birkenfeld, @amauryfa, @abalkin, @meadori, @berkerpeksag, @andresdelfino, @miss-islington
PRs
  • bpo-4260: Document that ctypes.xFUNCTYPE are decorators #7924
  • [3.7] bpo-4260: Document that ctypes.xFUNCTYPE are decorators (GH-7924) #8272
  • [3.6] bpo-4260: Document that ctypes.xFUNCTYPE are decorators (GH-7924) #8273
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    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 2018-07-13.14:05:29.865>
created_at = <Date 2008-11-05.05:51:02.885>
labels = ['easy', '3.8', 'type-feature', '3.7', 'docs']
title = 'Document that ctypes.xFUNCTYPE are decorators.'
updated_at = <Date 2018-07-13.14:05:29.864>
user = 'https://bugs.python.org/LambertDW'

    bugs.python.org fields:

    activity = <Date 2018-07-13.14:05:29.864>
actor = 'berker.peksag'
assignee = 'docs@python'
closed = True
closed_date = <Date 2018-07-13.14:05:29.865>
closer = 'berker.peksag'
components = ['Documentation']
creation = <Date 2008-11-05.05:51:02.885>
creator = 'LambertDW'
dependencies = []
files = []
hgrepos = []
issue_num = 4260
keywords = ['patch', 'easy']
message_count = 8.0
messages = ['75515', '75535', '75577', '320464', '321601', '321610', '321612', '321614']
nosy_count = 10.0
nosy_names = ['theller', 'georg.brandl', 'amaury.forgeotdarc', 'belopolsky', 'kevinwatters', 'LambertDW', 'meador.inge', 'berker.peksag', 'adelfino', 'miss-islington']
pr_nums = ['7924', '8272', '8273']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue4260'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']
    @lambertdw
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    lambertdw mannequin commented Nov 5, 2008

    http://docs.python.org/dev/3.0/library/ctypes.html#callback-functions

    ctypes.xFUNCTYPE are another opportunity to advertise decorators.
    Please consider inserting yet another qsort example written as a
    decorator, perhaps as follows. Or---it could be that I'm slow and the
    average pythonista will figure this out on first read.

    @CFUNCTYPE(c_int, POINTER(c_int), POINTER(c_int))
def py_cmp_func(*args):
    (a,b,) = (t[0] for t in args)
    print("py_cmp_func", a, b)
    return a-b

    qsort(ia,len(ia),sizeof(c_int),py_cmp_func)

    @lambertdw lambertdw mannequin assigned birkenfeld Nov 5, 2008
    @lambertdw lambertdw mannequin added docs Documentation in the Doc dir type-feature A feature request or enhancement labels Nov 5, 2008
    @kevinwatters
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    kevinwatters mannequin commented Nov 5, 2008

    As far as I know, the above code will fail randomly in release mode if
    you have multiple threads running Python, because when ctypes calls out
    to CFUNCTYPE functions, it releases the GIL.

    For decorating a python function to give to qsort, maybe you can use
    PYFUNCTYPE?

    @theller
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    theller commented Nov 6, 2008

    [David Lambert]

    > @CFUNCTYPE(c_int, POINTER(c_int), POINTER(c_int))
    > def py_cmp_func(*args):
    > (a,b,) = (t[0] for t in args)
    > print("py_cmp_func", a, b)
    > return a-b
    >
    > qsort(ia,len(ia),sizeof(c_int),py_cmp_func)

    [Kevin Watters]

    > As far as I know, the above code will fail randomly in release mode if
    > you have multiple threads running Python, because when ctypes calls out
    > to CFUNCTYPE functions, it releases the GIL.
    >
    > For decorating a python function to give to qsort, maybe you can use
    > PYFUNCTYPE?

    Kevin is wrong - the code is perfect! Sure does calling a CFUNCTYPE instance
    release the GIL, but ctypes aquires the GIL again before executing the python
    code in the wrapped py_cmp_func above.

    I guess that using PYFUNCTYPE instead would possibly crash because the call to
    'qsort' releases the GIL, and the PYFUNCTYPE instance assumes the GIL but does not
    acquire it.

    But I have no time to work on the docs, sorry.

    @admin admin mannequin assigned docspython and unassigned birkenfeld Oct 29, 2010
    @pppery pppery mannequin changed the title ctypes.xFUNCTYPE are decorators. Document that ctypes.xFUNCTYPE are decorators. May 7, 2016
    @csabella csabella added 3.7 (EOL) end of life 3.8 only security fixes labels Feb 25, 2018
    @andresdelfino
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    I suspect we'll be working on this PR a little, but a least it's a start to get this moving.

    @berkerpeksag
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    New changeset 379e9d6 by Berker Peksag (Andrés Delfino) in branch 'master':
    bpo-4260: Document that ctypes.xFUNCTYPE are decorators (GH-7924)
    379e9d6

    @miss-islington
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    New changeset 08c1da7 by Miss Islington (bot) in branch '3.7':
    bpo-4260: Document that ctypes.xFUNCTYPE are decorators (GH-7924)
    08c1da7

    @miss-islington
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    New changeset 083a836 by Miss Islington (bot) in branch '3.6':
    bpo-4260: Document that ctypes.xFUNCTYPE are decorators (GH-7924)
    083a836

    @berkerpeksag
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    I think we can now close this one. Thanks for the report, David, and thanks for the PR Andreas.

    (And thanks for creating and maintaining this awesome module for years, Thomas :))

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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