New codec which always raises an exception when used. This

codec can be used to effectively switch off string coercion
to Unicode.

Lib/encodings/undefined.py

@@ -0,0 +1,34 @@
+""" Python 'undefined' Codec
+
+    This codec will always raise a ValueError exception when being
+    used. It is intended for use by the site.py file to switch off
+    automatic string to Unicode coercion.
+
+Written by Marc-Andre Lemburg (mal@lemburg.com).
+
+(c) Copyright CNRI, All Rights Reserved. NO WARRANTY.
+
+"""
+import codecs
+
+### Codec APIs
+
+class Codec(codecs.Codec):
+
+    def encode(self,input,errors='strict'):
+        raise UnicodeError, "undefined encoding"
+
+    def decode(self,input,errors='strict'):
+        raise UnicodeError, "undefined encoding"
+
+class StreamWriter(Codec,codecs.StreamWriter):
+    pass
+        
+class StreamReader(Codec,codecs.StreamReader):
+    pass
+
+### encodings module API
+
+def getregentry():
+
+    return (Codec().encode,Codec().decode,StreamReader,StreamWriter)