Handling 3 operands in an expression without raising an exception

[Antoon Pardon]

Op 26-09-13 12:51, Νίκος schreef:
> Στις 26/9/2013 1:41 μμ, ο/η Antoon Pardon έγραψε:
>> Op 26-09-13 12:18, Νίκος schreef:
>>> Στις 26/9/2013 1:12 μμ, ο/η Antoon Pardon έγραψε:
>>>> Op 26-09-13 11:56, Νίκος schreef:
>>>
>>> It is far better than the ifs, even easier to read, i was just missing a
>>> [0] at the end.
>>>
>>> host = socket.gethostbyaddr( os.environ.get('HTTP_CF_CONNECTING_IP') or
>>> os.environ.get('REMOTE_ADDR') or  "Άγνωστη Προέλευση" )[0]
>>
>> No it is not. Your purpose was to have a line that wouldn't throw an
>> exception even if some environ variables were not available. That
>> means it shouldn't throw an exception when I execute the code. Guess
>> what happens:
>>
>>>>> socket.gethostbyaddr( os.environ.get('HTTP_CF_CONNECTING_IP') or
>> os.environ.get('REMOTE_ADDR') or  "Άγνωστη Προέλευση" )[0]
>> Traceback (most recent call last):
>>    File "<stdin>", line 1, in <module>
>> socket.gaierror: [Errno -2] Name or service not known
>>
>> You are just illustrating your lack of basic understaning.
> 
> I'm surepirsed, becaus eon my domain [superhost.gr] the same lien of
> code works withnout an error and it display the 'host' fileds properly.

You shoudn't be. This illustrates beautifully the difference between
understanding what one is doing and dabbling around until one stumbles
on something that currently works but that will stop working in other
circumstances.

> Perhaps its failing via shell or you do not have a web server installed
> to prepare the enviromental variables or i dont know what else to hink.

Yes it is failing via shell, but that doesn't matter. If your purpose
was to have that line working even if the environ variables were not
available, then the line should work from a shell too.

> But in my website this code runs at the probelm with no problem.

So? That just means that your website is not a good test environment
for checking whether the code works under all circumstances you want
it to work.

-- 
Antoon Pardon