[Python-ideas] syntax to continue into the next subsequent except block

[Scott Dial]

On 9/13/2012 5:05 PM, Paul Wiseman wrote:
> I think it would be useful if there was a way to skip into the next
> except block, perhaps with continue as I think it's currently always
> illegal to use in an except block. I don't believe there's currently a
> way to do this.
> 
> This is my reasoning, often there's multiple reasons for exceptions that
> raise the same exception, as an example an IOError might get raised for
> lots of different reasons. If you want to handle one or several of these
> reasons, you have to catch all exceptions of this type, but there's not
> really a way to "put back" the exception if it isn't the type you were
> after. For instance
> 
> try:
>     operation()
> except IOError as err:
>     if err.errno == 2:
>         do_something()
>     else:
>         continue #This would continue the except down to the next check,
> except Exception
> except Exception as err:
>     logger.error("Error performing operation: {}".format(err.message)")
>     some_clean_up()
>     raise
> 

"continue" already has a meaning that would make this ambiguous:

for i in range(10):
    try:
        raise IOError()
    except IOError as err:
        continue

Also, I would inevitably write what you want as:

try:
    operation()
except Exception as err:
    if isinstance(err, IOError):
        if err.errno == 2:
            do_something()
    else:
        logger.error(
            "Error performing operation: {}".format(err.message)")
        some_clean_up()
        raise

-- 
Scott Dial
scott at scottdial.com