Patch from jbalogh fixes issue #2282 (misnamed seekable() method).

Lib/io.py

@@ -1203,7 +1203,7 @@ class TextIOWrapper(TextIOBase):
     # were rendered by the decoder after feeding it those bytes.  We
     # use this to reconstruct intermediate decoder states in tell().
 
-    def _seekable(self):
+    def seekable(self):
         return self._seekable
 
     def flush(self):

Lib/test/test_io.py

@@ -895,6 +895,12 @@ class TextIOWrapperTest(unittest.TestCase):
         txt.seek(pos)
         self.assertEquals(txt.read(4), "BBB\n")
 
+    def test_issue2282(self):
+        buffer = io.BytesIO(self.testdata)
+        txt = io.TextIOWrapper(buffer, encoding="ascii")
+
+        self.assertEqual(buffer.seekable(), txt.seekable())
+
     def test_newline_decoder(self):
         import codecs
         decoder = codecs.getincrementaldecoder("utf-8")()

Misc/ACKS

@@ -33,6 +33,7 @@ Dwayne Bailey
 Stig Bakken
 Greg Ball
 Luigi Ballabio
+Jeff Balogh
 Michael J. Barber
 Chris Barker
 Quentin Barnes

Misc/NEWS

@@ -30,6 +30,8 @@ What's New in Python 3.0a3?
 Core and Builtins
 -----------------
 
+- Issue #2282: io.TextIOWrapper was not overriding seekable() from io.IOBase.
+
 - Issue #2115: Important speedup in setting __slot__ attributes.  Also 
   prevent a possible crash: an Abstract Base Class would try to access a slot 
   on a registered virtual subclass.