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Weakref proxy missing pass throughs for hash() and reversed() #84703

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rhettinger opened this issue May 5, 2020 · 2 comments
Closed

Weakref proxy missing pass throughs for hash() and reversed() #84703

rhettinger opened this issue May 5, 2020 · 2 comments
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3.8 only security fixes 3.9 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@rhettinger
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BPO 40523
Nosy @rhettinger, @pablogsal
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  • bpo-40523: Add pass-throughs for hash() and reversed() to weakref.proxy objects #19946
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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 2020-05-05.21:58:36.117>
created_at = <Date 2020-05-05.18:34:38.699>
labels = ['3.8', 'type-bug', 'library', '3.9']
title = 'Weakref proxy missing pass throughs for hash() and reversed()'
updated_at = <Date 2020-05-05.21:58:36.116>
user = 'https://github.com/rhettinger'

    bugs.python.org fields:

    activity = <Date 2020-05-05.21:58:36.116>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2020-05-05.21:58:36.117>
closer = 'pablogsal'
components = ['Library (Lib)']
creation = <Date 2020-05-05.18:34:38.699>
creator = 'rhettinger'
dependencies = []
files = []
hgrepos = []
issue_num = 40523
keywords = ['patch']
message_count = 2.0
messages = ['368197', '368211']
nosy_count = 2.0
nosy_names = ['rhettinger', 'pablogsal']
pr_nums = ['19946']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40523'
versions = ['Python 3.8', 'Python 3.9']
    @rhettinger
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    from weakref import proxy

class Alpha:
    def __len__(self):
        return 3
    def __reversed__(self):
        return iter('cba')
    def __hash__(self):
        return hash('abc')

a = Alpha()

# Direct use of the instance works
print(len(a))
print(list(reversed(a)))
print(hash(a))

# Proxies can use the dunder methods directly
r = proxy(a)
print(r.__len__())
print(list(r.__reversed__()))
print(r.__hash__())

    # Proxy fails for __reversed__ and __hash__
    print(len(r), 'This succeeds')
    try:
    print(list(reversed(r)))
    except TypeError:
    print('reverse(r) failed')
    try:
    print(hash(r))
    except TypeError:
    print('hash(r) failed')

    @rhettinger rhettinger added 3.8 only security fixes 3.9 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels May 5, 2020
    @pablogsal
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    New changeset 96074de by Pablo Galindo in branch 'master':
    bpo-40523: Add pass-throughs for hash() and reversed() to weakref.proxy objects (GH-19946)
    96074de

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