[PEAK] help with more info

Peter Damoc pdamoc at gmail.com
Mon Mar 24 05:04:08 EDT 2008

Thanks Phillip,

One silly question. Would it be possible to put a flag inside Trellis
components that would allow to turn on some kind of debugging where if
errors are thrown in rules they are made visible?
I was thinking about something like an optional debug decorator that gets
thrown automatically around every rule if the debug flag is turned ON.

Thank you again for your quick answer.

On Sat, Mar 22, 2008 at 6:48 PM, Phillip J. Eby <pje at telecommunity.com>

> At 06:19 PM 3/22/2008 +0200, Peter Damoc wrote:
> >I've started getting this error:
> >
> >AttributeError: Constants can't be changed
> >The problem is that I don't know what I'm doing wrong.
> >I used Trellis to manage some computations based on an external
> >object that contains a dictionary.
> >In a resync method I'm pushing the information inside a Trellis Dict
> object.
> >Everything worked fine till today when for some cases I get the above
> error.
> >
> >How can I get more information about what my code is trying do to
> illegally?
> >How can I get the name of the constant that its trying to change?
> Okay, here's what's happening.  You're actually getting a different
> error in your application; this is just masking it, because it's an
> error that happens during the rollback caused by the first
> error.  The specific issue is that an undo operation is adding a
> listener back to a cell that's become Constant, because it had no
> listeners.  (What's weird about that is that the setting of the cell
> to Constant should have been undone before it got back to this point
> in the rollback.  So something else weird is going on.)
> >here is a more complete trace:
> >
> >File "c:\Projects\BPM\patient_display.py", line 133, in OnBiodynamic
> >     dlg.panel.mp.resync(dlg.panel.meas)
> >   File "<peak.events.trellis.wrap wrapping
> > modules.biodynamic.measurements.resync at 0x01CC97F0>", line 5, in
> resync
> >   File
> > "c:\python25\lib\site-packages\Trellis-
> 0.6a1-py2.5.egg\peak\events\stm.py",
> > line 466, in atomically
> >     return super(Controller,self).atomically(self._process, func, args,
> kw)
> >   File
> > "c:\python25\lib\site-packages\Trellis-
> 0.6a1-py2.5.egg\peak\events\stm.py",
> > line 186, in atomically
> >     self.cleanup(*sys.exc_info())
> >   File
> > "c:\python25\lib\site-packages\Trellis-
> 0.6a1-py2.5.egg\peak\events\stm.py",
> > line 309, in cleanup
> >     return super(Controller, self).cleanup(*args)
> If you use pdb.pm() to get into this traceback, and walk up to this
> stack frame, you should be able to look at 'args' to find out what
> the original exception was that started the problem.  There really
> should be a better way to handle this, though.
> A possible workaround for the Constant part of the problem would be
> to ensure that any rule() in your application also has a value();
> that will ensure that the cell can never become constant (because
> it's writable).  But I wouldn't try that unless the above doesn't
> resolve your issue.
> (It's too bad there's no way to link multiple exceptions together in
> Python right now, it'd sure come in handy here.  That way, you could
> see the first exception as well as the cleanup exception.)

There is NO FATE, we are the creators.
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