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Unsupported IO operations should raise UnsupportedOperation #53539

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pitrou opened this issue Jul 18, 2010 · 4 comments
Closed

Unsupported IO operations should raise UnsupportedOperation #53539

pitrou opened this issue Jul 18, 2010 · 4 comments
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easy stdlib Python modules in the Lib dir topic-IO type-bug An unexpected behavior, bug, or error

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@pitrou
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pitrou commented Jul 18, 2010

BPO 9293
Nosy @amauryfa, @pitrou, @vstinner, @benjaminp, @skrah
Files
  • unsupported.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 2010-09-05.23:05:17.250>
created_at = <Date 2010-07-18.14:09:29.177>
labels = ['easy', 'type-bug', 'library', 'expert-IO']
title = 'Unsupported IO operations should raise UnsupportedOperation'
updated_at = <Date 2010-09-05.23:05:17.249>
user = 'https://github.com/pitrou'

    bugs.python.org fields:

    activity = <Date 2010-09-05.23:05:17.249>
actor = 'pitrou'
assignee = 'none'
closed = True
closed_date = <Date 2010-09-05.23:05:17.250>
closer = 'pitrou'
components = ['Library (Lib)', 'IO']
creation = <Date 2010-07-18.14:09:29.177>
creator = 'pitrou'
dependencies = []
files = ['18733']
hgrepos = []
issue_num = 9293
keywords = ['patch', 'easy']
message_count = 4.0
messages = ['110648', '110650', '115490', '115677']
nosy_count = 6.0
nosy_names = ['amaury.forgeotdarc', 'pitrou', 'vstinner', 'benjamin.peterson', 'stutzbach', 'skrah']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue9293'
versions = ['Python 3.2']
    @pitrou
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    pitrou commented Jul 18, 2010

    Some of them currently raise IOError. Fortunately, UnsupportedOperation inherits from IOError, which means compatibility can be preserved.

    Contrast:
>>> open("LICENSE").write("bar")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IOError: not writable

With:
>>> open("LICENSE", "rb").write(b"")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
io.UnsupportedOperation: write

Or:
>>> io.StringIO().fileno()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
io.UnsupportedOperation: fileno

    Or, unfortunately:

    >>> open("LICENSE", "rb", buffering=0).write(b"")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: File not open for writing

    @pitrou pitrou added stdlib Python modules in the Lib dir topic-IO easy type-bug An unexpected behavior, bug, or error labels Jul 18, 2010
    @pitrou
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    pitrou commented Jul 18, 2010

    Another kind of unsupported operation is non-absolute seeking on a TextIOWrapper:

    >>> open("LICENSE").seek(1, 1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IOError: can't do nonzero cur-relative seeks

    @pitrou
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    pitrou commented Sep 3, 2010

    Here is a patch.

    @pitrou
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    pitrou commented Sep 5, 2010

    Committed in r84544.

    @pitrou pitrou closed this as completed Sep 5, 2010
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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