I just noticed in the development docs that when a timeout on a socket occurs, socket.error is raised. I rather liked the idea that a different exception was raised for timeouts (I used Tim O'Malley's timeout_socket module). Making a TimeoutError exception a subclass of socket.error would be fine so you can catch it with existing code, but I could see recovering differently for a timeout as opposed to other possible errors:
sock.settimeout(5.0) try: data = sock.recv(8192) except socket.TimeoutError: # maybe requeue the request ... except socket.error, codes: # some more drastic solution is needed ...
+1 on your suggestion. Anyway, under windows, the current implementation returns incorrect socket.error code for timeout. I am working on the test suite as well as a fix for problem found. Once the code is bug free maybe we can put the TimeoutError in.
I will leave it to Guido for the approval of the change. When he comes back from his holiday.
The way I restructured the code it is impossible to distinguish a timeout error from other errors; you simply get the "no data available" error from the socket operation. This is the same error you'd get in non-blocking mode.
Before I recomplicate the code so that it can raise a separate error when the select fails, I'd like to understand the use case better. Why would you want to make this distinction? Requeueing the request (as in Skip's example) doesn't make sense IMO: you set the timeout for a reason, and that reason is that you want to give up if it takes too long. If you really intend to retry you're better of disabling the timeout!
If you really want to, you can already distinguish the timeout case, because you get an EAGAIN error then (maybe something else on Windows -- Bernard, if you have a fix for that, please send it to me).
So a -0 unless more evidence is brought forward.
--Guido van Rossum (home page: http://www.python.org/%7Eguido/)