[PEAK] problem with peak.io_events

Vladimir Iliev vlado at vintech.bg
Tue Sep 14 04:29:41 EDT 2004

Phillip J. Eby wrote:

> At 06:50 PM 9/13/04 +0300, Vladimir Iliev wrote:
>> Phillip J. Eby wrote:
>>> What OS are you using?
>> I tried on both Fedora Core 1 (python 2.3.4) and Gentoo (python 2.3.4).
> Hm.  On Python 2.3.3 and Red Hat 6.2, it works with or without the 
> itertools import.  On Python 2.2.3, I can't get it to work at all, 
> unless I fix another bug in your script, that I didn't notice previously.
> 'ss.signals()' returns an event object that is only valid for as long 
> as a reference to it is held.  The routine that calls it discards the 
> reference when it returns, so perhaps you're seeing some sort of GC 
> irregularity when you import itertools.  (There was a change to how GC 
> at shutdown works in Python 2.3.4.)  The following code works for me:
> class Comp(binding.Component):
>     def _setup(self):
>         def cb(*a): print 'bzzzzzzzzzzzzz'
>         ss = self.lookupComponent(ISignalSource)
>         ev = ss.signals(*tuple(signals))
>         ev.addCallback(cb)
>         MyTask(self, runEvery=1)
>         return ev   # save a reference to the event object
>     _setup = binding.Make(_setup, uponAssembly=True)
> I'm considering changing this aspect of certain peak.events, so that 
> they remain valid whenever they have callbacks, rather than requiring 
> a reference to be held at all times.  But it may be a while before I 
> can get to that.  In the meantime, whenever you request dynamic I/O 
> events like 'readable()' or 'signals()', you should hold onto the 
> event for as long as you'd like to receive callbacks.
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Now it works. Thanks!

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