rot_13 codec not working

[cool-RR]

BPO	13600
Nosy	@ezio-melotti, @cool-RR, @akheron
Superseder	bpo-7475: codecs missing: base64 bz2 hex zlib hex_codec ...

^{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 2011-12-14.10:48:42.871>
created_at = <Date 2011-12-14.08:56:36.169>
labels = ['type-bug', 'library', 'docs']
title = 'rot_13 codec not working'
updated_at = <Date 2011-12-14.10:48:42.869>
user = 'https://github.com/cool-RR'

bugs.python.org fields:

activity = <Date 2011-12-14.10:48:42.869>
actor = 'petri.lehtinen'
assignee = 'docs@python'
closed = True
closed_date = <Date 2011-12-14.10:48:42.871>
closer = 'petri.lehtinen'
components = ['Documentation', 'Library (Lib)']
creation = <Date 2011-12-14.08:56:36.169>
creator = 'cool-RR'
dependencies = []
files = []
hgrepos = []
issue_num = 13600
keywords = []
message_count = 5.0
messages = ['149431', '149434', '149436', '149437', '149438']
nosy_count = 4.0
nosy_names = ['ezio.melotti', 'cool-RR', 'docs@python', 'petri.lehtinen']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = None
status = 'closed'
superseder = '7475'
type = 'behavior'
url = 'https://bugs.python.org/issue13600'
versions = ['Python 3.3']

[cool-RR]

The rot_13 codec is supposed to work like this, no?

>>> 'qwerty'.encode('utf-8')
b'qwerty'
>>> 'qwerty'.encode('rot_13')
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    'qwerty'.encode('rot_13')
TypeError: encoder did not return a bytes object (type=str)

>>> b'qwerty'.decode('utf-8')
'qwerty'
>>> b'qwerty'.decode('rot_13')
Traceback (most recent call last):
  File "<pyshell#2>", line 1, in <module>
    b'qwerty'.decode('rot_13')
  File "C:\Python32\lib\encodings\rot_13.py", line 19, in decode
    return (input.translate(rot13_map), len(input))
AttributeError: 'memoryview' object has no attribute 'translate'

[ezio-melotti]

See bpo-7475.

[akheron]

Ram Rachum wrote:

The rot_13 codec is supposed to work like this, no?

No it isn't. In Python 3, str.encode() always encodes to bytes and bytes.decode() always decodes to str. IOW, str.encode() encodes text (Unicode) to data (bytes), and bytes.decode() decodes data to text. ROT-13 is not a character encoding, so it cannot be used in this manner.

It's still available in the codecs module, though:

>>> import codecs
>>> codecs.lookup('rot-13').encode('qwerty')
('djregl', 6)

Other text->text and bytes->bytes codecs are also available there.

[cool-RR]

Then I suggest replacing this error message:

encoder did not return a bytes object (type=str)

and this one:

'memoryview' object has no attribute 'translate'

With something like:

Please use `codecs.lookup('rot-13').encode`

[akheron]

Issue bpo-7475 discusses fixing the error messages, too.