file accepts 'rU+' as a mode #46354

brettcannon · 2008-02-12T22:55:09Z

BPO	2091
Nosy	@brettcannon, @amauryfa, @pitrou, @vstinner, @larryhastings, @rbtcollins, @benjaminp, @bitdancer, @berkerpeksag, @serhiy-storchaka
PRs	bpo-2091: Fix typo in exception message #12987 [3.7] bpo-2091: Fix typo in exception message (GH-12987) #12988
Files	issue2091.diff issue2091-2.patch: Updated patch for new io issue2091-3.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 = None
closed_at = <Date 2015-07-25.18:45:53.834>
created_at = <Date 2008-02-12.22:55:09.244>
labels = ['interpreter-core', 'type-bug', 'expert-IO']
title = "file accepts 'rU+' as a mode"
updated_at = <Date 2019-04-27.20:39:08.758>
user = 'https://github.com/brettcannon'

bugs.python.org fields:

activity = <Date 2019-04-27.20:39:08.758>
actor = 'berker.peksag'
assignee = 'none'
closed = True
closed_date = <Date 2015-07-25.18:45:53.834>
closer = 'rbcollins'
components = ['Interpreter Core', 'IO']
creation = <Date 2008-02-12.22:55:09.244>
creator = 'brett.cannon'
dependencies = []
files = ['9697', '22217', '39980']
hgrepos = []
issue_num = 2091
keywords = ['patch', 'needs review']
message_count = 19.0
messages = ['62343', '63741', '104582', '116954', '116955', '136425', '137409', '223368', '223810', '247133', '247193', '247212', '247215', '247334', '247365', '247366', '247370', '341010', '341013']
nosy_count = 14.0
nosy_names = ['brett.cannon', 'amaury.forgeotdarc', 'pitrou', 'vstinner', 'larry', 'rbcollins', 'benjamin.peterson', 'jeff.balogh', 'r.david.murray', 'python-dev', 'jcon', 'francismb', 'berker.peksag', 'serhiy.storchaka']
pr_nums = ['12987', '12988']
priority = 'high'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue2091'
versions = ['Python 2.7', 'Python 3.4', 'Python 3.5']

brettcannon · 2008-02-12T22:55:09Z

The docs on file's constructor says that the 'U' mode should not work
with '+', and yet 'rU+' does not throw an error.

jeffbalogh · 2008-03-17T19:52:39Z

Attaching a patch that checks for '+' in the mode string, updates the
docs, and tests bad mode strings.

tseaver · 2010-04-29T20:27:41Z

I can confirm that:

the patch applies cleanly to the release26-maint branch, with the
exception of the Misc/NEWS portion::

  $ hg branch
  release26-maint
  $ ./python -E -tt Lib/test/regrtest.py test_file
  test_file
  1 test OK.
  $ patch -p0 < /tmp/issue2091.diff 
  patching file Objects/fileobject.c
  Hunk #1 succeeded at 209 (offset 54 lines).
  Hunk #2 succeeded at 2269 (offset 194 lines).
  patching file Misc/NEWS
  Hunk #1 FAILED at 12.
  1 out of 1 hunk FAILED -- saving rejects to file Misc/NEWS.rej
  patching file Lib/test/test_file.py
  Hunk #1 succeeded at 176 (offset 55 lines).

the added test fails before rebuilding Objects/fileobject.c::

  $ ./python -E -tt Lib/test/regrtest.py test_file
  test_file
  test test_file failed -- Traceback (most recent call last):
    File "/home/tseaver/projects/hg-repo/py-2.6/Lib/test/test_file.py", line 181, in testModeStrings
      f = open(TESTFN, mode)
  IOError: [Errno 2] No such file or directory: '@test'
  
  1 test failed:
      test_file

the added test passes after rebuilding Objects/fielobject.c::

  $ make
  gcc -pthread -c -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes  -I. -IInclude -I./Include   -DPy_BUILD_CORE -o Objects/fileobject.o Objects/fileobject.c
  ...
  $ ./python -E -tt Lib/test/regrtest.py test_file
  test_file
  1 test OK.

BreamoreBoy · 2010-09-20T16:37:34Z

The patch is now way out of date to the extent that I can't find the code in fileobject.c, perhaps I'm just blind Can someone please provide a new patch, thanks.

amauryfa · 2010-09-20T17:33:02Z

Of course, the implementation is now in the io module:
Modules/_io/_iomodule.c *and* Lib/_pyio.py

elibendersky · 2011-05-21T09:29:42Z

In Python 3, the documentation no longer mentions that 'U' should not work with '+' (or 'w' or 'a', for that matter), and the code throws ValueError if 'U' is used with 'w' or 'a', but not '+'.

On the other hand, the documentation *does* mention that 'U' is for backwards compatibility and shouldn't be used with new code.

In light of this, how do you suggest to proceed with this issue?

jcon · 2011-06-01T01:00:00Z

It seems to me that adding the proper check is a good idea. It also may not be obvious to some that 'U' is now more or less an alias for 'r'. I have updated the patch so that it at least applies.

I also removed a redundant reading = 1

francismb · 2014-07-17T20:32:11Z

On the other hand, the documentation *does* mention that
'U' is for backwards compatibility and shouldn't be used
with new code.

Shouldn't be some deprecation warning somewhere?

serhiy-storchaka · 2014-07-24T05:27:00Z

In Python 3.4+ 'U' already emits deprecation warning.

rbtcollins · 2015-07-22T16:48:46Z

Updated patch. I'm not going to apply right now - giving it a little time to let folk chime on whether this should be applied all the way back to 3.4, or not.

My inclination is to only apply it to 3.6.

bitdancer · 2015-07-23T13:23:01Z

I agree, a change that emits an error where none was emitted before should only go in the next release. With a what's new entry.

It is possible there should be a deprecation or -3 warning in 2.7, but I'm not sure it is worth the effort.

rbtcollins · 2015-07-23T14:57:19Z

@larry - should this go in 3.5, or would you rather it not?

serhiy-storchaka · 2015-07-23T15:21:06Z

I would add a warning in 3.4- (or 3.5-). The 'U' mode should not work
with '+', and it can't work with '+' correctly. This is a bug that we can decide not fix by raising an exception.

larryhastings · 2015-07-25T10:14:20Z

Yeah, considering how long this bug has been sitting around, I think we can wait for one more release for the fix. 3.6 please.

python-dev · 2015-07-25T18:43:33Z

New changeset 1a5bbb31f740 by Robert Collins in branch 'default':

Issue bpo-2091: error correctly on open() with mode 'U' and '+'
https://hg.python.org/cpython/rev/1a5bbb31f740

rbtcollins · 2015-07-25T18:45:39Z

@larry thanks - that was my inclination too. Applied to 3.6

@serhiy I've not done a warning in 3.4/3.5 because - the behaviour is already broken, this patch just catches it a lot earlier (on open rather than subsequent operations).

serhiy-storchaka · 2015-07-25T18:59:22Z

Perhaps the 'U' mode should just raise an exception in 3.6.

berkerpeksag · 2019-04-27T19:40:48Z

New changeset 21a9ba1 by Berker Peksag in branch 'master':
bpo-2091: Fix typo in exception message (GH-12987)
21a9ba1

berkerpeksag · 2019-04-27T20:39:09Z

New changeset f5972cc by Berker Peksag (Miss Islington (bot)) in branch '3.7':
bpo-2091: Fix typo in exception message (GH-12987)
f5972cc

brettcannon added interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error labels Feb 12, 2008

devdanzin mannequin added the topic-IO label Apr 28, 2009

rbtcollins closed this as completed Jul 25, 2015

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

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file accepts 'rU+' as a mode #46354

file accepts 'rU+' as a mode #46354

brettcannon commented Feb 12, 2008

brettcannon commented Feb 12, 2008

jeffbalogh mannequin commented Mar 17, 2008

tseaver commented Apr 29, 2010

BreamoreBoy mannequin commented Sep 20, 2010

amauryfa commented Sep 20, 2010

elibendersky mannequin commented May 21, 2011

jcon mannequin commented Jun 1, 2011

francismb mannequin commented Jul 17, 2014

serhiy-storchaka commented Jul 24, 2014

rbtcollins commented Jul 22, 2015

bitdancer commented Jul 23, 2015

rbtcollins commented Jul 23, 2015

serhiy-storchaka commented Jul 23, 2015

larryhastings commented Jul 25, 2015

python-dev mannequin commented Jul 25, 2015

rbtcollins commented Jul 25, 2015

serhiy-storchaka commented Jul 25, 2015

berkerpeksag commented Apr 27, 2019

berkerpeksag commented Apr 27, 2019

file accepts 'rU+' as a mode #46354

file accepts 'rU+' as a mode #46354

Comments

brettcannon commented Feb 12, 2008

brettcannon commented Feb 12, 2008

jeffbalogh mannequin commented Mar 17, 2008

tseaver commented Apr 29, 2010

BreamoreBoy mannequin commented Sep 20, 2010

amauryfa commented Sep 20, 2010

elibendersky mannequin commented May 21, 2011

jcon mannequin commented Jun 1, 2011

francismb mannequin commented Jul 17, 2014

serhiy-storchaka commented Jul 24, 2014

rbtcollins commented Jul 22, 2015

bitdancer commented Jul 23, 2015

rbtcollins commented Jul 23, 2015

serhiy-storchaka commented Jul 23, 2015

larryhastings commented Jul 25, 2015

python-dev mannequin commented Jul 25, 2015

rbtcollins commented Jul 25, 2015

serhiy-storchaka commented Jul 25, 2015

berkerpeksag commented Apr 27, 2019

berkerpeksag commented Apr 27, 2019