Minor tidy up of zmqterminal.completer

IPython/frontend/zmqterminal/completer.py

@@ -3,6 +3,10 b' import readline'
 import time
 import sys
 stdout = sys.stdout
+
+class TimeoutError(Exception):
+    pass
+
 class ClientCompleter2p(object):
     """Client-side completion machinery.
 
@@ -23,30 +27,25 b' class ClientCompleter2p(object):'
                                 dict(text=text, line=line))
         # send completion request to kernel
         # Give the kernel up to 0.5s to respond
-        msg_matches = None
         for i in range(5):
            if self.km.xreq_channel.was_called():
               msg_xreq =  self.km.xreq_channel.get_msg()
-              if msg["header"]['session'] == msg_xreq["parent_header"]['session'] :
-                 if msg_xreq["content"]["status"] == 'ok' :
-                    if msg_xreq["msg_type"] == "complete_reply" :
-                       msg_matches = msg_xreq["content"]["matches"]
-                       #break
+                if msg["header"]['session'] == msg_xreq["parent_header"]['session'] and \
+                                msg_xreq["content"]["status"] == 'ok' and \
+                                msg_xreq["msg_type"] == "complete_reply" :
+                    return msg_xreq["content"]["matches"]
+                       
            time.sleep(0.1)
-        return msg_matches   
+        raise TimeoutError
     
     def complete(self, text, state):
         if state == 0 :
+            try:
            self.matches = self.complete_request(text)
-           
-        if self.matches is None:
-           self.matches = []
+            except TimeoutError:
            print('WARNING: Kernel timeout on tab completion.')
-        #print self.matches
+        
         try:
             return self.matches[state]
         except IndexError:
             return None
-        
-        
-