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inspect.getcallargs() attempts to iterate over None #65015

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jlowin mannequin opened this issue Mar 1, 2014 · 5 comments
Closed

inspect.getcallargs() attempts to iterate over None #65015

jlowin mannequin opened this issue Mar 1, 2014 · 5 comments
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@1st1
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stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@jlowin
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jlowin mannequin commented Mar 1, 2014

BPO 20816
Nosy @ncoghlan, @1st1
Files
  • issue20816.patch
    		•

    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/1st1'
closed_at = <Date 2014-03-27.22:28:05.793>
created_at = <Date 2014-03-01.16:00:50.831>
labels = ['type-bug', 'library']
title = 'inspect.getcallargs() attempts to iterate over None'
updated_at = <Date 2014-03-27.22:28:51.581>
user = 'https://bugs.python.org/jlowin'

    bugs.python.org fields:

    activity = <Date 2014-03-27.22:28:51.581>
actor = 'yselivanov'
assignee = 'yselivanov'
closed = True
closed_date = <Date 2014-03-27.22:28:05.793>
closer = 'python-dev'
components = ['Library (Lib)']
creation = <Date 2014-03-01.16:00:50.831>
creator = 'jlowin'
dependencies = []
files = ['34260']
hgrepos = []
issue_num = 20816
keywords = ['patch']
message_count = 5.0
messages = ['212509', '212512', '212513', '214986', '214987']
nosy_count = 4.0
nosy_names = ['ncoghlan', 'python-dev', 'yselivanov', 'jlowin']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue20816'
versions = ['Python 3.3', 'Python 3.4']
    @jlowin
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    jlowin mannequin commented Mar 1, 2014

    Tested in Python 3.3 and Python 3.4.0rc1 5e05d7d3db9c

    If a function has keyword-only arguments but no keyword-only defaults, then calling inspect.getcallargs with no arguments results in the wrong TypeError being raised.

    Example:

    >> import inspect
    >> def fn(*, a):
    >> pass
    >> inspect.getcallargs(fn)

    Result:
    TypeError: argument of type 'NoneType' is not iterable

    Expected Result:
    TypeError: fn() missing 1 required keyword-only argument: 'a'

    @jlowin jlowin mannequin added stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Mar 1, 2014
    @jlowin
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    jlowin mannequin commented Mar 1, 2014

    I created a patch to resolve this.

    If a function has keyword-only arguments, then inspect.getcallargs checks if the argument is in kwonlydefaults. However, kwonlydefaults is None if no defaults were specified. In that situation, 'kwarg in kwonlydefaults' raises the TypeError.

    The quick fix is simply to test kwonlydefaults before testing if kwarg is in it.

    The test for this situation is a little verbose because a TypeError is expected and one is raised, just the wrong one, so I parse the error message.

    @jlowin
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    jlowin mannequin commented Mar 1, 2014

    Apologies, the patch is attached here.

    @1st1 1st1 self-assigned this Mar 1, 2014
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    python-dev mannequin commented Mar 27, 2014

    New changeset 3de2e729d0fb by Yury Selivanov in branch 'default':
    inspect: Fix getcallargs() to raise correct TypeError
    http://hg.python.org/cpython/rev/3de2e729d0fb

    New changeset 070dfca74610 by Yury Selivanov in branch '3.4':
    inspect: Fix getcallargs() to raise correct TypeError
    http://hg.python.org/cpython/rev/070dfca74610

    @python-dev python-dev mannequin closed this as completed Mar 27, 2014
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    1st1 commented Mar 27, 2014

    Fixed for 3.4.1 and 3.5.
    Thank you Jeremiah!

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