Matteo Landi <landima...@gmail.com> wrote:
> On Sun, Oct 17, 2010 at 6:58 PM, <tinn...@isbd.co.uk> wrote:
> > I'm writing some code that writes to a mbox file and want to retry
> > locking the mbox file a few times before giving up. I can't see a
> > really tidy way to implement this.
> >
> > Currently I have something like:-
> >
> > dest = mailbox.mbox(mbName, factory=None)
> >
> > for tries in xrange(3):
> > try:
> > dest.lock()
> > #
> > #
> > # Do some stuff to the mbox file
> > #
> > dest.unlock()
> > break # done what we need, carry on
> >
> > except mailbox.ExternalClashError:
> > log("Destination locked, try " + str(tries))
> > time.sleep(1)
> > # and try again
> >
> > ... but this doesn't really work 'nicely' because the break after
> > dest.unlock() takes me to the same place as running out of the number
> > of tries in the for loop. I need a way to handle the case where we
> > run out of tries (and *haven't* done what we needed to do) separately
> > from the case where it worked OK.
> >
> > I can see all sorts of messy ways to handle this with a flag of some
> > sort but is there a proper elegant way of doing it?
> >
> You can use the 'else' keyword outside the for loop:
>
> for <condition>:
> if <condition>:
> break
> else
> <some operations>
>
> The execution will step inside the else branch if the for loop ends
> normally, i.e. without encountering a break keyword.
> Hope it helps.
>
Thank you! I'd looked at 'else' inside the 'try' but hadn't thought
of looking at the 'else' that goes with 'for'. That does just what I
need.
--
Chris Green
--
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