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Implementation-depended pickling floats with protocol 0 #67285

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serhiy-storchaka opened this issue Dec 21, 2014 · 6 comments
Closed

Implementation-depended pickling floats with protocol 0 #67285

serhiy-storchaka opened this issue Dec 21, 2014 · 6 comments
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@serhiy-storchaka
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stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@serhiy-storchaka
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BPO 23096
Nosy @pitrou, @avassalotti, @serhiy-storchaka
Files
  • pickle_float_repr.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/serhiy-storchaka'
closed_at = <Date 2015-02-15.12:35:43.683>
created_at = <Date 2014-12-21.08:10:33.232>
labels = ['type-bug', 'library']
title = 'Implementation-depended pickling floats with protocol 0'
updated_at = <Date 2015-02-15.12:35:43.683>
user = 'https://github.com/serhiy-storchaka'

    bugs.python.org fields:

    activity = <Date 2015-02-15.12:35:43.683>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2015-02-15.12:35:43.683>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2014-12-21.08:10:33.232>
creator = 'serhiy.storchaka'
dependencies = []
files = ['38039']
hgrepos = []
issue_num = 23096
keywords = ['patch']
message_count = 6.0
messages = ['232992', '232995', '233024', '233027', '235550', '236034']
nosy_count = 4.0
nosy_names = ['pitrou', 'alexandre.vassalotti', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue23096'
versions = ['Python 3.5']
    @serhiy-storchaka
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    Python and C implementations of pickle produce different results when pickle floats with protocol 0.

    >>> pickle.dumps(4.2, 0)
b'F4.2000000000000002\n.'
>>> pickle._dumps(4.2, 0)
b'F4.2\n.'

    @serhiy-storchaka serhiy-storchaka added stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Dec 21, 2014
    @serhiy-storchaka
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    Python implementation uses repr(value) and C implementation uses '%.17g' % value.

    @avassalotti
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    The repr for floats was changed some time ago to use a shorter decimal strings when possible. Both representations should yield the same float value once decoded. If we want to make the C and Python implementations of pickle consistent, then we should pick on what the Python version does currently: i.e., call repr on the float.

    @pitrou
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    pitrou commented Dec 22, 2014

    This looks less like a bug than an enhancement request.

    @serhiy-storchaka
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    Here is a patch.

    @serhiy-storchaka serhiy-storchaka self-assigned this Feb 15, 2015
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    python-dev mannequin commented Feb 15, 2015

    New changeset 8c9121993eb5 by Serhiy Storchaka in branch 'default':
    Issue bpo-23096: Pickle representation of floats with protocol 0 now is the same
    https://hg.python.org/cpython/rev/8c9121993eb5

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

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    @avassalotti @pitrou @serhiy-storchaka