[Tutor] Error handling

[Sithembewena Lloyd Dube]

That is because 'errno' is a property on the exception object called 'e',
not the other way around.

On Sun, Mar 25, 2012 at 7:12 AM, Michael Lewis <mjolewis at gmail.com> wrote:

>
>
> On Sat, Mar 24, 2012 at 3:51 PM, Colton Myers <colton.myers at gmail.com>wrote:
>
>>  I am having a bit of trouble understanding what is going on below. What
>> does the "e" in "except OSError, e:" do?
>> Any other help you can provide regarding errno would be extremely
>> appreciated. I've done help() and dir() on it, but I am not really
>> understanding what's going on with "e.errno != errno.EEXIST:"
>>
>> Basically, that `except` block is catching all exceptions of type
>> OSError, and storing the exception in variable `e`.  This variable does not
>> have to be called `e`, but that's the most commonly-used variable name.
>>
>> Once you have the exception stored (in this case in the variable `e`),
>> you can then see what type of exception, using the `errno` property of the
>> exception.  You can read about the different types here:
>>
>> http://docs.python.org/library/errno.html
>>
>>  import os, errnotry:
>>     os.makedirs('a/b/c')except OSError, e:
>>     if e.errno != errno.EEXIST:
>>         raise
>>
>> In this particular section, it's catching any OSError, and then if it
>> turns out that the error was "File Exists", it is raising that exception
>> again, to be either caught by an encapsulating try block, or which will
>> bring the program to a halt with an exception shown by the interpreter.
>>
>> Is that the behavior you are going for?  Any more confusion?
>>
>
> Why wouldn't it be errno.e instead of e.errno?
>
>>
>> --
>> Colton Myers
>>
>>
>
>
> --
> Michael J. Lewis
>
> mjolewis at gmail.com
> 415.815.7257
>
>
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-- 
Regards,
Sithembewena Lloyd Dube
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