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textwrap.dedent() fails when largest common whitespace is a substring of smallest leading whitespace #66026

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robertjli mannequin opened this issue Jun 22, 2014 · 16 comments
Closed

textwrap.dedent() fails when largest common whitespace is a substring of smallest leading whitespace #66026

robertjli mannequin opened this issue Jun 22, 2014 · 16 comments
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@serhiy-storchaka
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easy stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@robertjli
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robertjli mannequin commented Jun 22, 2014

BPO 21827
Nosy @rhettinger, @pitrou, @ezio-melotti, @bitdancer, @zware, @serhiy-storchaka, @jayvdb, @ilevkivskyi
Files
  • cb18733ce8f1.diff
  • 34e88a05562f.diff
  • issue21827.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 2015-10-28.19:50:48.557>
created_at = <Date 2014-06-22.16:44:47.794>
labels = ['easy', 'type-bug', 'library']
title = 'textwrap.dedent() fails when largest common whitespace is a substring of smallest leading whitespace'
updated_at = <Date 2015-10-28.19:50:48.555>
user = 'https://bugs.python.org/robertjli'

    bugs.python.org fields:

    activity = <Date 2015-10-28.19:50:48.555>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2015-10-28.19:50:48.557>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2014-06-22.16:44:47.794>
creator = 'robertjli'
dependencies = []
files = ['35727', '35731', '40873']
hgrepos = ['258']
issue_num = 21827
keywords = ['patch', 'easy']
message_count = 16.0
messages = ['221277', '221281', '221282', '221283', '221287', '221292', '224544', '224547', '253593', '253596', '253600', '253605', '253609', '253612', '253620', '253621']
nosy_count = 12.0
nosy_names = ['rhettinger', 'pitrou', 'ezio.melotti', 'r.david.murray', 'python-dev', 'zach.ware', 'serhiy.storchaka', 'puppet', 'robertjli', 'yjchen', 'jayvdb', 'levkivskyi']
pr_nums = []
priority = 'high'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue21827'
versions = ['Python 2.7', 'Python 3.4', 'Python 3.5', 'Python 3.6']
    @robertjli
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    robertjli mannequin commented Jun 22, 2014

    Failing test case: " \tboo\n \tghost"

    expected: " \tboo\n\tghost"
    returns: " \tboo\n \tghost"

    @robertjli robertjli mannequin added stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Jun 22, 2014
    @rhettinger rhettinger self-assigned this Jun 22, 2014
    @rhettinger
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    Confirmed that the test case fails on 2.7, 3.4, and 3.5

    @rhettinger
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    This one isn't hard. Would you like to make a patch? If not, I get to it this evening.

    @yjchen
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    yjchen mannequin commented Jun 22, 2014

    Hi Raymond- Rob and I have a patch ready. We are figuring out how to upload/submit it. New to this... :)

    @robertjli
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    robertjli mannequin commented Jun 22, 2014

    YJ and I are adding a patch and an additional test.

    @zware
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    zware commented Jun 22, 2014

    Raymond confirmed that the issue exists on 2.7 and 3.4, so we'll keep those in the version list. Whoever makes the commit will take care of backporting the patch, though.

    @puppet
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    puppet mannequin commented Aug 2, 2014

    Tested and it works fine on CentOS 6.4 in 2.7, 3.4 and 3.5

    @rhettinger
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    I've got it from here.

    @jayvdb
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    jayvdb mannequin commented Oct 28, 2015

    Not surprising also occurs on Python 3.2, 3.3, & 3.6.
    I'm not sure whether fixes like this are suitable to be merged into 3.2/3.3.(is there a document describing this?)

    @serhiy-storchaka
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    LGTM. But the implementation can be more efficient. Here is optimized patch.

    34e88a05562f.diff:
    $ ./python -m timeit -s 'import textwrap; s = "{0} x\n{0}\tx\n".format(" "*100)' -- 'textwrap.dedent(s)'
    10000 loops, best of 3: 87.5 usec per loop
    $ ./python -m timeit -s 'import textwrap; s = "{0} x\n{0}\tx\n".format(" "*1000)' -- 'textwrap.dedent(s)'
    1000 loops, best of 3: 780 usec per loop

    bpo-21827.patch:
    $ ./python -m timeit -s 'import textwrap; s = "{0} x\n{0}\tx\n".format(" "*100)' -- 'textwrap.dedent(s)'
    10000 loops, best of 3: 51 usec per loop
    $ ./python -m timeit -s 'import textwrap; s = "{0} x\n{0}\tx\n".format(" "*1000)' -- 'textwrap.dedent(s)'
    1000 loops, best of 3: 395 usec per loop

    @bitdancer
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    It's one of the PEPs (I forget which one). We only apply non-security fixes to the most recent non-development branch...except that for now we also apply bug fixes to 2.7. So, 2.7, 3.5, and 3.6 are the targets for this issue.

    @rhettinger
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    Serhiy, your way looks best. Go ahead with it.

    @serhiy-storchaka
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    I thought that 3.4 will switch to "security fixes only" mode after releasing first release since releasing 3.5.0. It was so with 3.2 and 3.3.

    @bitdancer
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    You are right, I'd forgotten we hadn't done 3.4 final yet.

    @python-dev
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    python-dev mannequin commented Oct 28, 2015

    New changeset faeeb8dbe432 by Serhiy Storchaka in branch '3.4':
    Issue bpo-21827: Fixed textwrap.dedent() for the case when largest common
    https://hg.python.org/cpython/rev/faeeb8dbe432

    New changeset c307ae7b3d9f by Serhiy Storchaka in branch '2.7':
    Issue bpo-21827: Fixed textwrap.dedent() for the case when largest common
    https://hg.python.org/cpython/rev/c307ae7b3d9f

    New changeset 3f29be82c944 by Serhiy Storchaka in branch '3.5':
    Issue bpo-21827: Fixed textwrap.dedent() for the case when largest common
    https://hg.python.org/cpython/rev/3f29be82c944

    New changeset 8d3932671e48 by Serhiy Storchaka in branch 'default':
    Issue bpo-21827: Fixed textwrap.dedent() for the case when largest common
    https://hg.python.org/cpython/rev/8d3932671e48

    @serhiy-storchaka
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    Thank you Robert for your report and patch.

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