New submission from Stefan Behnel <sco...@users.sourceforge.net>:
The xml.etree.ElementTree package in the Python 3.x standard library breaks
compatibility with existing ET 1.2 code. The serialiser returns a unicode
string when no encoding is passed. Previously, the serialiser was guaranteed to
return a byte string. By default, the string was 7-bit ASCII compatible.
This behavioural change breaks all code that relies on the default behaviour of
ElementTree. Since there is no longer a default encoding in Python 3, unicode
strings are incompatible with byte strings, which means that the result of the
serialisation can no longer be written to a file, for example.
XML is well defined as a stream of bytes. Redefining it as a unicode string *by
default* is hard to understand at best.
Finally, it would have been good to look at the other ET implementation before
introducing such a change. The lxml.etree package has had support for
serialising XML into a unicode string for years, and does so in a clear, safe
and explicit way. It requires the user to pass the 'unicode' (Py3 'str') type
as encoding parameter, e.g.
tree.tostring(encoding=str)
which is explicit enough to make it clear that this is different from a normal
encoding.
----------
components: Library (Lib)
messages: 100333
nosy: scoder
severity: normal
status: open
title: Serialiser in ElementTree returns unicode strings in Py3k
type: behavior
versions: Python 3.1, Python 3.2
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue8047>
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