On Wed, May 2, 2012 at 1:12 PM, Prasad, Ramit <ramit.pra...@jpmorgan.com> wrote:
>> > I have multiple objects, where any of them can serve my purpose..
>> However
>> > some objects might not have some dependencies. I can not tell before
>> hand if
>> > the all the dependencies exsit. What i want to is begin processing from
>> the
>> > 1st object, if no exception is raised, i am done.. if an exception is
>> > raised, the next object is tried, etc Something like
>> >
>> > objs = [... ]
>> > try:
>> > obj = objs[0]
>> > obj.make()
>> > except Exception, e:
>> > try:
>> > obj = objs[1]
>> > obj.make()
>> > except Exception, e:
>> > try:
>> > obj = objs[2]
>> > obj.make()
>> > except Exception, e:
>> > continue
>> >
>> > The problem is the length of the list of objs is variable... How can i
>> do
>> > this?
>>
>>
>> for obj in objs:
>> try:
>> obj.make()
>> except Exception:
>> continue
>> else:
>> break
>> else:
>> raise RuntimeError('No object worked')
>
>
> I think you misunderstand the else clauses.
>
>>>> for obj in [ 1,2,3,4 ]:
> ... try:
> ... print obj
> ... except Exception:
> ... print 'EXCEPTION'
> ... else:
> ... print 'NO EXCEPTION'
> ... else:
> ... print 'NO OBJECTS'
> ...
> 1
> NO EXCEPTION
> 2
> NO EXCEPTION
> 3
> NO EXCEPTION
> 4
> NO EXCEPTION
> NO OBJECTS
You left out the break in the try clause's else that I had. That break
statement causes the for loop to exit early if there is no exception,
and thus the for loop's else clause does not run:
>>> for obj in [ 1,2,3,4 ]:
... try:
... print obj
... except Exception:
... print 'EXCEPTION'
... else:
... print 'NO EXCEPTION'
... break
... else:
... print 'NO OBJECTS'
...
1
NO EXCEPTION
>
>
> Ramit
>
>
> Ramit Prasad | JPMorgan Chase Investment Bank | Currencies Technology
> 712 Main Street | Houston, TX 77002
> work phone: 713 - 216 - 5423
>
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