[issue9821] Support PEP 383 on Windows: mbcs support of surrogateescape error handler

[Marc-Andre Lemburg]

Marc-Andre Lemburg <mal at egenix.com> added the comment:

STINNER Victor wrote:
> 
> New submission from STINNER Victor <victor.stinner at haypocalc.com>:
> 
> It would be nice to support PEP 383 (surrogateescape) on Windows, but the mbcs codec doesn't support it for performance reason. The Windows functions to encode/decode MBCS don't give the index of the unencodable/undecodable character/byte. For encoding, we can try to encode character by character (but be careful of surrogate pairs) and check that the character is a Python lone surrogate character or not (character in range U+DC80..U+DCFF). For decoding, it is more complex because MBCS can be a multibyte encoding, eg. cp65001 (Microsoft variant of utf-8, see #6058). So it's not possible to encode byte per byte and we should write an heuristic to guess the right number of bytes for each call to the decode function.
> 
> --
> 
> A completly different solution is to get the MBCS code page and use the Python code page codec (eg. "cp1252") instead of "mbcs" encoding, because Python cpXXXX codecs support all Python error handlers. Example (with Python 2.6):
> 
>>>> print(u"abcŁdef".encode("cp1252", "replace"))
> abc?def
>>>> print(u"abcŁdef".encode("cp1252", "ignore"))
> abcdef
>>>> print(u"abcŁdef".encode("cp1252", "backslashreplace"))
> abc\u0141def

That would certainly be a better approach, provided that our
cp-encodings are indeed compatible with the Windows variants
(which unfortunately tend to often use slightly different
mappings).

We could then also alias 'mbcs' to the cp-encoding (sort of
like the reverse of what we do in site.py:aliasmbcs().

----------
nosy: +lemburg
title: Support PEP 383 on Windows: mbcs support of surrogateescape error handler -> Support PEP 383 on Windows: mbcs support of	surrogateescape error handler

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