[Twisted-Python] how to write a safe catch-all

Chris Withers chris at simplistix.co.uk
Thu Sep 30 06:48:40 EDT 2010

On 30/09/2010 04:45, exarkun at twistedmatrix.com wrote:
> On 12:52 am, chris at simplistix.co.uk wrote:
>> Because I haven't found any permutation that doesn't result in the
>> LoopingCall's calls to `loop` from stopping after the exception.
>> I would be more than ecstatic to be proved wrong ;-)
> You keep saying the LoopingCall stops.  It does not stop.  It is waiting
> for a result.

What result is it waiting for and how do I pass that from the `loop` 
function in my first example when the exception is caught?

> If you provide it with a result, it will proceed.

See above: how do I do that?

> Glyph
> suggested a number of (hackfully) mechanisms you might use to provide it
> with a result.

Why do you say hackfully? I'm trying to build a scheduler that is 
resilient to failure in a scheduled task. Yes, of course I want to fix 
that failure, but I don't want a failure in one scheduled task to 
prevent any further scheduled tasks from being executed...

> I suggested another way (fix the broken code, or at
> least supply enough information for someone else to fix it).

For all I know, it's already fixed in a newer version of Twisted 
(unfortunately, I can't move this project to a newer version of Twisted) 
but once I have a robust scheduler, I'll certainly do my best to report 
the underlying failure to you guys properly...


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