Index: Lib/asyncore.py
===================================================================
--- Lib/asyncore.py	(revisione 80760)
+++ Lib/asyncore.py	(copia locale)
@@ -50,6 +50,7 @@
 import socket
 import sys
 import time
+import warnings
 
 import os
 from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, \
@@ -265,6 +266,8 @@
                 status.append(repr(self.addr))
         return '<%s at %#x>' % (' '.join(status), id(self))
 
+    __str__ = __repr__
+
     def add_channel(self, map=None):
         #self.log_info('adding channel %s' % self)
         if map is None:
@@ -396,7 +399,15 @@
     # cheap inheritance, used to pass all other attribute
     # references to the underlying socket object.
     def __getattr__(self, attr):
-        return getattr(self.socket, attr)
+        try:
+            retattr = getattr(self.socket, attr)
+        except AttributeError:
+            raise AttributeError("%s instance has no attribute '%s'"
+                                 %(self.__class__.__name__, attr))
+        else:
+            warnings.warn("cheap inheritance is deprecated", DeprecationWarning, 
+                          stacklevel=2)
+            return retattr
 
     # log and log_info may be overridden to provide more sophisticated
     # logging and warning methods. In general, log is for 'hit' logging
Index: Lib/test/test_asyncore.py
===================================================================
--- Lib/test/test_asyncore.py	(revisione 80760)
+++ Lib/test/test_asyncore.py	(copia locale)
@@ -5,6 +5,7 @@
 import socket
 import sys
 import time
+import warnings
 
 from test import test_support
 from test.test_support import TESTFN, run_unittest, unlink
@@ -305,6 +306,22 @@
                     'warning: unhandled accept event']
         self.assertEquals(lines, expected)
 
+    def test_issue_8594(self):
+        d = asyncore.dispatcher(socket.socket())
+        # make sure the error message no longer refers to the socket
+        # object but the dispatcher instance instead
+        self.assertRaisesRegexp(AttributeError, 'dispatcher instance',
+                                getattr, d, 'foo')
+        # The cheap inheritance with the underlying socket is supposed
+        # to still work but a DeprecationWarning is expected.
+        # Note: this test is supposed to be removed in next major Python
+        # version.
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+            family = d.family
+            self.assertEqual(family, socket.AF_INET)
+            self.assertTrue(len(w) == 1)
+            self.assertTrue(issubclass(w[0].category, DeprecationWarning))
 
 
 class dispatcherwithsend_noread(asyncore.dispatcher_with_send):