Re: Handling 3 operands in an expression without raising an exception

From	Νίκος <nikos.gr33k@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: Handling 3 operands in an expression without raising an exception
Date	2013-09-26 19:58 +0300
Organization	A noiseless patient Spider
Message-ID	<l21p2r$ilf$1@dont-email.me> (permalink)
References	(7 earlier) <mailman.350.1380194717.18130.python-list@python.org> <l219tq$o2c$1@dont-email.me> <mailman.354.1380200021.18130.python-list@python.org> <l21d5u$cit$1@dont-email.me> <mailman.355.1380205373.18130.python-list@python.org>

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Στις 26/9/2013 5:22 μμ, ο/η Dave Angel έγραψε:
> On 26/9/2013 09:34, Νίκος wrote:
>
>> Στις 26/9/2013 3:53 μμ, ο/η Antoon Pardon έγραψε:
>>> Op 26-09-13 14:39, Νίκος schreef:
>>>> Yes, you are right, in my shell it fails too givign the same error
>>>> message as yours, while on the other had in the websste is working.
>>>>
>>>> Can you explain this please?
>>>> why doesnt it fail to both enviroments?
>>>
>>> Your site and your shell are two different environments. The state
>>> of the website environment lets your code succeed while the state
>>> of the shell environment, doesn't.
>>>
>> What modification does it need to also work in the shell environmentthe
>> [0] at the end is what complicates things.
>
> Not at all.  What complicates/confuses things is trying to do too much
> in one line.
>
> The line is trying to solve two separate things.  You might now
> understand the first of them; the fetching of multiple environment
> variables that may or may not exist.
>
> The second thing is the function call to gethostbyname().  If fed
> invalid data, this call will throw an exception.  So you need to either
> put it in a try/catch or somehow pretend that you can know what
> constitutes invalid data.  One example of invalid data is your default
> string.  Another might be if one of those environment variables exists,
> but isn't reasonable.  And a third might be if the domain server
> temporarily refuses to recognize a valid hostname.
>
> I'd say you need to put the gethostbyname() in a try/catch, and then
> supply some reasonable bogus string for host.  Only you will know what
> to use there;  depending on what you're going to use it for.
>
>
> ipval = (os.environ.get('HTTP_CF_CONNECTING_IP') or
> os.environ.get('REMOTE_ADDR', "Please throw a gaierror exception")
> try:
>       host = socket.gethostbyaddr(ipval) [0]
> except socket.gaierror as exc;
>       host = "Unknown host"
>
> I don't know the gethostbyaddr(), so i don't know if there are other
> exceptions you should also try to catch.
>

Indeed this logic you follow is hethe best i have seen so far.
But actually i have 2 variables that relay on a proper ip address.

ipval = ( os.environ.get('HTTP_CF_CONNECTING_IP') or 
os.environ.get('REMOTE_ADDR', "UnKnown Origin") )
try:
	gi = pygeoip.GeoIP('/usr/local/share/GeoIPCity.dat')
	city = gi.time_zone_by_addr( ipval )
	host = socket.gethostbyaddr( ipval ) [0]
except socket.gaierror as e:
	city = host = "UnKnown Origin"

But then what if in case of an error i needed different string set to be 
assigned on city and host respectively?

As i ahve it know in case of n address related error i get the smae 
sting for both of them.

Thread

Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 10:26 +0300
  Re: Handling 3 operands in an expression without raising an exception Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-09-26 10:48 +0300
    Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 10:51 +0300
      Re: Handling 3 operands in an expression without raising an exception Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-09-26 11:12 +0300
        Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 11:39 +0300
          Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 11:46 +0300
            Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 11:50 +0300
              Re: Handling 3 operands in an expression without raising an exception Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-09-26 12:20 +0300
          Re: Handling 3 operands in an expression without raising an exception Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-09-26 12:04 +0300
            Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 12:45 +0300
          Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-26 11:07 +0200
            Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 12:31 +0300
              Re: Handling 3 operands in an expression without raising an exception Maarten <maarten.sneep@knmi.nl> - 2013-09-26 02:52 -0700
              Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-26 12:01 +0200
              Re: Handling 3 operands in an expression without raising an exception "James Harris" <james.harris.1@gmail.com> - 2013-09-26 11:53 +0100
          Re: Handling 3 operands in an expression without raising an exception alex23 <wuwei23@gmail.com> - 2013-09-27 10:05 +1000
        Re: Handling 3 operands in an expression without raising an exception Chris Angelico <rosuav@gmail.com> - 2013-09-26 18:41 +1000
        Re: Handling 3 operands in an expression without raising an exception Tim Golden <mail@timgolden.me.uk> - 2013-09-26 09:47 +0100
  Re: Handling 3 operands in an expression without raising an exception Nobody <nobody@nowhere.com> - 2013-09-26 09:55 +0100
    Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 12:56 +0300
      Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-26 12:12 +0200
        Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 13:18 +0300
          Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-26 12:41 +0200
            Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 13:51 +0300
              Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-26 13:07 +0200
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 14:25 +0300
                Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-26 13:47 +0200
                Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-26 14:42 +0000
              Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-26 11:24 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 15:39 +0300
                Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-26 14:53 +0200
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 16:34 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-26 14:22 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-26 19:58 +0300
                Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-26 20:16 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-27 01:14 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-26 22:55 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-27 12:19 +0300
                Re: Handling 3 operands in an expression without raising an exception Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-27 09:26 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-27 13:04 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-27 10:43 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-27 14:15 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-27 12:17 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-27 15:51 +0300
                Re: Handling 3 operands in an expression without raising an exception rusi <rustompmody@gmail.com> - 2013-09-28 10:29 -0700
                Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-27 15:16 +0000
                Re: Handling 3 operands in an expression without raising an exception Grant Edwards <invalid@invalid.invalid> - 2013-09-27 16:04 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-27 19:47 +0300
                Re: Handling 3 operands in an expression without raising an exception Neil Cerutti <neilc@norwich.edu> - 2013-09-27 16:56 +0000
                Re: Handling 3 operands in an expression without raising an exception Grant Edwards <invalid@invalid.invalid> - 2013-09-27 17:00 +0000
                Re: Handling 3 operands in an expression without raising an exception Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-27 13:19 -0400
                Re: Handling 3 operands in an expression without raising an exception Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-09-27 18:32 +0100
                Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-27 18:49 +0000
                Re: Handling 3 operands in an expression without raising an exception Grant Edwards <invalid@invalid.invalid> - 2013-09-27 18:54 +0000
                Re: Handling 3 operands in an expression without raising an exception Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-27 15:21 -0400
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-28 01:06 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-27 22:26 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-28 12:33 +0300
                Re: Handling 3 operands in an expression without raising an exception Chris Angelico <rosuav@gmail.com> - 2013-09-28 20:19 +1000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-28 16:23 +0300
                Re: Handling 3 operands in an expression without raising an exception Andreas Perstinger <andipersti@gmail.com> - 2013-09-28 17:02 +0200
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-28 19:14 +0300
                Re: Handling 3 operands in an expression without raising an exception Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-09-28 18:53 +0100
                Re: Handling 3 operands in an expression without raising an exception Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-28 14:21 -0400
                Re: Handling 3 operands in an expression without raising an exception Zero Piraeus <z@etiol.net> - 2013-09-28 15:38 -0300
                Re: Handling 3 operands in an expression without raising an exception Neil Cerutti <neilc@norwich.edu> - 2013-09-30 11:32 +0000
                Re: Handling 3 operands in an expression without raising an exception Chris Angelico <rosuav@gmail.com> - 2013-09-30 21:53 +1000
                Re: Handling 3 operands in an expression without raising an exception Neil Cerutti <neilc@norwich.edu> - 2013-09-30 12:56 +0000
                Re: Handling 3 operands in an expression without raising an exception Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-09-28 19:45 +0100
                Re: Handling 3 operands in an expression without raising an exception Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-28 19:20 +0000
                Re: Handling 3 operands in an expression without raising an exception Chris Angelico <rosuav@gmail.com> - 2013-09-29 09:04 +1000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-29 10:35 +0300
                Re: Handling 3 operands in an expression without raising an exception Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-09-29 12:35 +0300
                Re: Handling 3 operands in an expression without raising an exception Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-29 09:48 +0000
                Re: Handling 3 operands in an expression without raising an exception Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-09-29 14:04 +0300
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-29 14:14 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-29 11:27 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-29 14:34 +0300
                Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-29 21:15 +0000
                Re: Handling 3 operands in an expression without raising an exception Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-09-30 16:07 +0100
                Re: Handling 3 operands in an expression without raising an exception Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-09-29 15:24 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-29 09:50 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-29 13:17 +0300
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-29 10:57 +0000
                Re: Handling 3 operands in an expression without raising an exception Chris Angelico <rosuav@gmail.com> - 2013-09-29 23:58 +1000
                Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-29 21:01 +0000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-29 14:06 +0300
                Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-29 12:48 +0200
                Re: Handling 3 operands in an expression without raising an exception Piet van Oostrum <piet@vanoostrum.org> - 2013-09-29 13:24 -0400
                Re: Handling 3 operands in an expression without raising an exception MRAB <python@mrabarnett.plus.com> - 2013-09-29 18:44 +0100
                Re: Handling 3 operands in an expression without raising an exception Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-29 14:45 -0400
                Re: Handling 3 operands in an expression without raising an exception Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-09-30 16:05 +0100
                Re: Handling 3 operands in an expression without raising an exception Ben Finney <ben+python@benfinney.id.au> - 2013-09-29 11:35 +1000
                Re: Handling 3 operands in an expression without raising an exception Chris Angelico <rosuav@gmail.com> - 2013-09-28 11:59 +1000
                Re: Handling 3 operands in an expression without raising an exception Νίκος <nikos.gr33k@gmail.com> - 2013-09-28 12:14 +0300
                Re: Handling 3 operands in an expression without raising an exception Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-09-28 15:53 +0200
                Re: Handling 3 operands in an expression without raising an exception Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-28 12:15 -0400
                Re: Handling 3 operands in an expression without raising an exception Robert Kern <robert.kern@gmail.com> - 2013-09-28 12:18 +0100
                Re: Handling 3 operands in an expression without raising an exception giacomo boffi <pecore@pascolo.net> - 2013-09-29 17:28 +0200
                Re: Handling 3 operands in an expression without raising an exception Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-29 12:07 -0400
                Re: Handling 3 operands in an expression without raising an exception giacomo boffi <pecore@pascolo.net> - 2013-09-29 23:39 +0200
                Re: Handling 3 operands in an expression without raising an exception giacomo boffi <pecore@pascolo.net> - 2013-09-29 23:49 +0200
                Re: Handling 3 operands in an expression without raising an exception Chris Angelico <rosuav@gmail.com> - 2013-09-30 02:18 +1000
                Re: Handling 3 operands in an expression without raising an exception Dave Angel <davea@davea.name> - 2013-09-26 20:37 +0000
      Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-26 14:38 +0000
      Re: Handling 3 operands in an expression without raising an exception Denis McMahon <denismfmcmahon@gmail.com> - 2013-09-26 14:38 +0000
  Re: Handling 3 operands in an expression without raising an exception Gene Heskett <gheskett@wdtv.com> - 2013-09-29 13:32 -0400

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