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From: Albert Hopkins <marduk@letterboxes.org>
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Subject: Re: error in except
Date: Mon, 04 Feb 2013 19:58:01 -0500
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Xref: csiph.com comp.lang.python:38155



On Mon, Feb 4, 2013, at 04:49 PM, Rodrick Brown wrote:
> For the life of me I cant figure out why this exception is being thrown.
> How could I use pdb to debug this?
> 
> $ python udp_local2.py server
>   File "udp_local2.py", line 36
>     except:
>          ^
> SyntaxError: invalid syntax
> 
> 
> #!/usr/bin/env python
> 
> import random, socket, sys
> s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
> 
> MAX = 65535
> PORT = 1060
> 
> if 2 <= len(sys.argv) <= 3 and sys.argv[1] == 'server':
>     interface = sys.argv[2] if len(sys.argv) > 2 else ''
>     s.bind((interface, PORT))
>     print 'Listening at', s.getsockname()
>     while True:
>         data, address = s.recvfrom(MAX)
>         if random.randint(0, 1):
>             print 'The client at', address, 'says:', repr(data)
>             s.sendto('Your data was %d bytes' % len(data), address)
>         else:
>             print 'Pretending to drop packet from', address
> 
> elif len(sys.argv) == 3 and sys.argv[1] == 'client':
>     hostname = sys.argv[2]
>     s.connect((hostname, PORT))
>     print 'Client socket name is', s.getsockname()
>     delay = 0.1
>     while True:
>         s.send('This is another message')
>         print 'Waiting up to', delay, 'seconds for a reply'
>         s.settimeout(delay)
>         try:
>             data = s.recv(MAX)
>         except socket.timeout:
>             delay *= 2
>             if delay > 2.0:
>                 raise RuntimeError('I think the server is down')
>             except:
>                 raise
>             else:
>                 break
>         print 'The server says', repr(data)
>     else:
>         print >> sys.stderr, 'usage: %d server [<interfae>]' %
>         sys.argv[0]
>         print >> sys.stderr, '   or: %d client <host>' % sys.argv[0]
>         sys.exit(2)
> -- 
> http://mail.python.org/mailman/listinfo/python-list

Your "except" statement is on the same level as "if delay > 2.0"..
effectively:

if delay > 2.0
  ...
except:

which is not valid syntax.  Excepts go with try: blocks, not if: blocks.