I need to parse a byte stream as an XML document and,
afterwards, access the same document as a Unicode
string. I would prefer to rely on the parser's
charset-determining logic, and the 'property_encoding'
feature
("http://www.python.org/sax/properties/encoding") seems
to offer exactly this information.

However, the default Expat parser doesn't support this
feature.

---
from xml.sax import make_parser, handler
from xml.sax.xmlreader import InputSource
from sys import stdin

p = make_parser()

# Should not fail. Should it return None, or UTF-8?
assert(p.getProperty(handler.property_encoding) == None)

source = InputSource()
source.setByteStream(stdin)

p.parse(source)

# Should now be the name of the actual encoding used
assert(p.getProperty(handler.property_encoding) != None)
---

This raises SAXNotRecognizedException.

Is there another SAX parser I could use instead?

The URL referenced in msg54124 gives a 404.  It is also used as the property_encoding in the sax handler module.  Could this be fixed in 3.2 or can this issue be closed?

The behaviour is unchanged in Python 3.1 and the sample program still fails.

This is still an issue so the sax handler module property_encoding attribute be set to what URL?

Mark, the "http://www.python.org/sax/properties/encoding" is not meant to be a web page. It's like an attribute name, but fully qualified so that attributes given by different organizations don't clash.
(There may be different usages of "encoding": is it the one set by the user, or the one determined by the parser? according to Python docs, here it's both)

Python's default Expat parser doesn't support this feature, so the present behavior is correct.
Proper support should not be difficult to add, with a XmlDeclHandler.