diff -r 0b2d4089180c Lib/urllib/request.py
--- a/Lib/urllib/request.py	Wed Apr 10 17:01:38 2013 -0400
+++ b/Lib/urllib/request.py	Sat Apr 13 17:16:51 2013 -0400
@@ -371,42 +371,40 @@
             raise TypeError("expected BaseHandler instance, got %r" %
                             type(handler))
 
+        action_lookup = {
+            'open': self.handle_open,
+            'response': self.process_response,
+            'request': self.process_request,
+            'error': self.handle_error
+        }
+
         added = False
-        for meth in dir(handler):
-            if meth in ["redirect_request", "do_open", "proxy_open"]:
+        for method in dir(handler):
+            if method in ["redirect_request", "do_open", "proxy_open"]:
                 # oops, coincidental match
                 continue
 
-            i = meth.find("_")
-            protocol = meth[:i]
-            condition = meth[i+1:]
+            split_method_name = method.split('_')
+            protocol = split_method_name[0]
+            event = split_method_name[1] if len(split_method_name) > 1 else ''
+            
+            if event not in action_lookup:
+                continue
+            else:
+                if event == 'error':
+                    kind = split_method_name[2] if len(split_method_name) > 2 else ''
+                    try:
+                        kind = int(kind)
+                    except ValueError:
+                        pass
+                    action = action_lookup[event].get(protocol, {})
+                    self.handle_error[protocol] = action
+                else:
+                    kind = protocol
+                    action = action_lookup[event]
 
-            if condition.startswith("error"):
-                j = condition.find("_") + i + 1
-                kind = meth[j+1:]
-                try:
-                    kind = int(kind)
-                except ValueError:
-                    pass
-                lookup = self.handle_error.get(protocol, {})
-                self.handle_error[protocol] = lookup
-            elif condition == "open":
-                kind = protocol
-                lookup = self.handle_open
-            elif condition == "response":
-                kind = protocol
-                lookup = self.process_response
-            elif condition == "request":
-                kind = protocol
-                lookup = self.process_request
-            else:
-                continue
-
-            handlers = lookup.setdefault(kind, [])
-            if handlers:
-                bisect.insort(handlers, handler)
-            else:
-                handlers.append(handler)
+            handlers = action.setdefault(kind, [])
+            bisect.insort(handlers, handler)
             added = True
 
         if added: