MacRoman Encoding Bug (OHM vs. OMEGA)

[seanbpalmer]

BPO	1382096
Nosy	@malemburg

^{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/malemburg'
closed_at = <Date 2005-12-16.14:47:09.000>
created_at = <Date 2005-12-16.02:22:35.000>
labels = ['expert-unicode']
title = 'MacRoman Encoding Bug (OHM vs. OMEGA)'
updated_at = <Date 2005-12-16.14:47:09.000>
user = 'https://bugs.python.org/seanbpalmer'

bugs.python.org fields:

activity = <Date 2005-12-16.14:47:09.000>
actor = 'lemburg'
assignee = 'lemburg'
closed = True
closed_date = None
closer = None
components = ['Unicode']
creation = <Date 2005-12-16.02:22:35.000>
creator = 'seanbpalmer'
dependencies = []
files = []
hgrepos = []
issue_num = 1382096
keywords = []
message_count = 2.0
messages = ['27087', '27088']
nosy_count = 2.0
nosy_names = ['lemburg', 'seanbpalmer']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue1382096'
versions = ['Python 2.4']

[seanbpalmer]

The file encodings/mac_roman.py in Python 2.4.1
contains the following incorrect character definition
on line 96:

    0x00bd: 0x2126, # OHM SIGN

This should read:

    0x00bd: 0x03A9, # GREEK CAPITAL LETTER OMEGA

Presumably this bug occurred due to a misreading, given
that OHM and OMEGA having the same glyph. Evidence that
the OMEGA interpretation is correct:

0xBD 0x03A9 # GREEK CAPITAL LETTER OMEGA
-http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/ROMAN.TXT

Further evidence can be found by Googling for MacRoman
tables. This bug means that, for example, the following
code gives a UnicodeEncodeError when it shouldn't do:

>> u'\u03a9'.encode('macroman')

For a workaround, I've been using the following code:

>>> import codecs
>>> from encodings import mac_roman
>>> mac_roman.decoding_map[0xBD] = 0x03A9
>>> mac_roman.encoding_map =
codecs.make_encoding_map(mac_roman.decoding_map)

And then, to use the example above:

>>> u'\u03a9'.encode('macroman')
'\xbd'
>>> 

Thanks,

--
Sean B. Palmer

[malemburg]

Logged In: YES
user_id=38388

This has been fixed in CVS and Python 2.5 will include the fix.

A backport is not possible, because we've changed the way
charmap codecs work in 2.5.