diff -r ad51ed93377c Lib/shlex.py
--- a/Lib/shlex.py	Thu Oct 11 00:11:26 2012 -0700
+++ b/Lib/shlex.py	Thu Oct 11 14:17:26 2012 -0500
@@ -27,14 +27,10 @@
             self.instream = sys.stdin
             self.infile = None
         self.posix = posix
-        if posix:
-            self.eof = None
-        else:
-            self.eof = ''
         self.commenters = '#'
         self.wordchars = ('abcdfeghijklmnopqrstuvwxyz'
                           'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_')
-        if self.posix:
+        if self._posix:
             self.wordchars += ('ßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿ'
                                'ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞ')
         self.whitespace = ' \t\r\n'
@@ -53,6 +49,17 @@
             print('shlex: reading from %s, line %d' \
                   % (self.instream, self.lineno))
 
+    def _get_posix(self):
+        return self._posix
+
+    def _set_posix(self, posix):
+        self._posix = posix
+        if posix:
+            self.eof = None
+        else:
+            self.eof = ''
+    posix = property(_get_posix, _set_posix)
+
     def push_token(self, tok):
         "Push a token onto the stack popped by the get_token method"
         if self.debug >= 1:
@@ -134,21 +141,21 @@
                 elif nextchar in self.whitespace:
                     if self.debug >= 2:
                         print("shlex: I see whitespace in whitespace state")
-                    if self.token or (self.posix and quoted):
+                    if self.token or (self._posix and quoted):
                         break   # emit current token
                     else:
                         continue
                 elif nextchar in self.commenters:
                     self.instream.readline()
                     self.lineno = self.lineno + 1
-                elif self.posix and nextchar in self.escape:
+                elif self._posix and nextchar in self.escape:
                     escapedstate = 'a'
                     self.state = nextchar
                 elif nextchar in self.wordchars:
                     self.token = nextchar
                     self.state = 'a'
                 elif nextchar in self.quotes:
-                    if not self.posix:
+                    if not self._posix:
                         self.token = nextchar
                     self.state = nextchar
                 elif self.whitespace_split:
@@ -156,7 +163,7 @@
                     self.state = 'a'
                 else:
                     self.token = nextchar
-                    if self.token or (self.posix and quoted):
+                    if self.token or (self._posix and quoted):
                         break   # emit current token
                     else:
                         continue
@@ -168,13 +175,13 @@
                     # XXX what error should be raised here?
                     raise ValueError("No closing quotation")
                 if nextchar == self.state:
-                    if not self.posix:
+                    if not self._posix:
                         self.token = self.token + nextchar
                         self.state = ' '
                         break
                     else:
                         self.state = 'a'
-                elif self.posix and nextchar in self.escape and \
+                elif self._posix and nextchar in self.escape and \
                      self.state in self.escapedquotes:
                     escapedstate = self.state
                     self.state = nextchar
@@ -201,22 +208,22 @@
                     if self.debug >= 2:
                         print("shlex: I see whitespace in word state")
                     self.state = ' '
-                    if self.token or (self.posix and quoted):
+                    if self.token or (self._posix and quoted):
                         break   # emit current token
                     else:
                         continue
                 elif nextchar in self.commenters:
                     self.instream.readline()
                     self.lineno = self.lineno + 1
-                    if self.posix:
+                    if self._posix:
                         self.state = ' '
-                        if self.token or (self.posix and quoted):
+                        if self.token or (self._posix and quoted):
                             break   # emit current token
                         else:
                             continue
-                elif self.posix and nextchar in self.quotes:
+                elif self._posix and nextchar in self.quotes:
                     self.state = nextchar
-                elif self.posix and nextchar in self.escape:
+                elif self._posix and nextchar in self.escape:
                     escapedstate = 'a'
                     self.state = nextchar
                 elif nextchar in self.wordchars or nextchar in self.quotes \
@@ -233,7 +240,7 @@
                         continue
         result = self.token
         self.token = ''
-        if self.posix and not quoted and result == '':
+        if self._posix and not quoted and result == '':
             result = None
         if self.debug > 1:
             if result:
diff -r ad51ed93377c Lib/test/test_shlex.py
--- a/Lib/test/test_shlex.py	Thu Oct 11 00:11:26 2012 -0700
+++ b/Lib/test/test_shlex.py	Thu Oct 11 14:17:26 2012 -0500
@@ -189,6 +189,12 @@
             self.assertEqual(shlex.quote("test%s'name'" % u),
                              "'test%s'\"'\"'name'\"'\"''" % u)
 
+    def testPosixAttribute(self):
+        s = shlex.shlex(r"", posix=False)
+        s.posix = True
+        self.assertEqual(s.eof, None)
+        s.posix = False
+        self.assertEqual(s.eof, '')
 
 # Allow this test to be used with old shlex.py
 if not getattr(shlex, "split", None):