newbie question about confusing exception handling in urllib

[Ian Kelly]

On Tue, Apr 9, 2013 at 5:41 AM,  <cabbar at gmail.com> wrote:
>         try:
>             response = urllib.request.urlopen(request)
>             content = response.read()
>         except BaseException as ue:
>             if (isinstance(ue, socket.timeout) or (hasattr(ue, "reason") and isinstance(ue.reason, socket.timeout)) or isinstance(ue, ConnectionResetError)):
>                 print("REQUEST TIMED OUT")

I'm surprised nobody has yet pointed out that you can catch multiple
specific exception types in the except clause rather than needing to
organize them under a catch-all base class.  These two code blocks are
basically equivalent:

try:
    do_stuff()
except BaseException as ue:
    if isinstance(ue, (socket.timeout, ConnectionResetError)):
        handle_it()
    else:
        raise

try:
    do_stuff()
except (socket.timeout, ConnectionResetError) as ue:
    handle_it()

Cheers,
Ian