[vtkusers] python exceptions patch needed for vtk 5.6
Lic. José M. Rodriguez Bacallao
jmrbcu at gmail.com
Tue Jun 1 11:36:27 EDT 2010
thanks, I will analyze that later, thanks for your answer!!!
On Tue, Jun 1, 2010 at 10:30 AM, David Gobbi <david.gobbi at gmail.com> wrote:
> The CallDataType attribute is read by the vtkPythonCommand, which is
> working behind the scenes. You can read vtkPythonCommand.cxx to see
> how it works. I think that a having a method called GetCallDataType()
> would be easier for people to understand than having an attribute.
>
> David
>
>
> On Tue, Jun 1, 2010 at 7:11 AM, Lic. José M. Rodriguez Bacallao
> <jmrbcu at gmail.com> wrote:
>> well, I can confirm that Charl's patch work very well. The only thing
>> to worry is from raising an exception within an observer in python but
>> for me this is not a major problem. Right now, I am using this patch
>> with vtk 5.4.2 because is nice to see python exceptions and for my
>> threading issues (the last is a big issue for me), this is the only
>> patch I have seen for vtk python bindings that address the GIL issue.
>> I have tested this patch in linux and soon will be doing the same with
>> windows because my application must support windows/linux and possible
>> MacOSX.
>>
>> David, I like your way of catching errors but ins this code:
>>
>> ==== python code ====
>> import vtk
>>
>> class ErrorObserver:
>>
>> def __init__(self):
>> self.__ErrorOccurred = False
>> self.__ErrorMessage = None
>> self.CallDataType = 'string0'
>>
>> def __call__(self, obj, event, message):
>> self.__ErrorOccurred = True
>> self.__ErrorMessage = message
>>
>> def ErrorOccurred(self):
>> occ = self.__ErrorOccurred
>> self.__ErrorOccurred = False
>> return occ
>>
>> def ErrorMessage(self):
>> return self.__ErrorMessage
>>
>> e = ErrorObserver()
>>
>> a = vtk.vtkImageReader()
>> a.AddObserver('ErrorEvent', e)
>>
>> print "doing update"
>> a.Update()
>> if e.ErrorOccurred():
>> print e.ErrorMessage()
>> ==== python code ====
>>
>> where do you use self.CallDataType?
>>
>>
>> On Sun, May 30, 2010 at 9:03 PM, David Gobbi <david.gobbi at gmail.com> wrote:
>>> Hi Florian,
>>>
>>> Here is an example of how to make an error observer in python. Most
>>> of the code is straightforward. The __call__ method is needed because
>>> VTK-Python observers must be callable objects. The only messy part is
>>> the "CallDataType", which is needed because in C++ the VTK object
>>> passes the error message as a "void *" instead of as a properly typed
>>> object, so the python observer needs a hint that the "void *" is a
>>> "char *".
>>>
>>> ==== python code ====
>>> import vtk
>>>
>>> class ErrorObserver:
>>>
>>> def __init__(self):
>>> self.__ErrorOccurred = False
>>> self.__ErrorMessage = None
>>> self.CallDataType = 'string0'
>>>
>>> def __call__(self, obj, event, message):
>>> self.__ErrorOccurred = True
>>> self.__ErrorMessage = message
>>>
>>> def ErrorOccurred(self):
>>> occ = self.__ErrorOccurred
>>> self.__ErrorOccurred = False
>>> return occ
>>>
>>> def ErrorMessage(self):
>>> return self.__ErrorMessage
>>>
>>> e = ErrorObserver()
>>>
>>> a = vtk.vtkImageReader()
>>> a.AddObserver('ErrorEvent', e)
>>>
>>> print "doing update"
>>> a.Update()
>>> if e.ErrorOccurred():
>>> print e.ErrorMessage()
>>> ==== python code ====
>>>
>>>
>>>
>>> On Sun, May 30, 2010 at 3:47 AM, Florian Bruckner <e0425375 at gmail.com> wrote:
>>>> OK, for me this means that I will use vtk observers, since I need a portable
>>>> solution that runs on a default vtk installation.
>>>>
>>>> @gobbi: could you please send me a short example, of how you use these
>>>> observers in python?
>>>>
>>>> nevertheless it would be nice to see this patch in some future vtk releases.
>>>> If the only problem are these unreachable code warnings in windows, why
>>>> can't you simply add some helper-functions that execute this otherwise
>>>> unreachable code? Since I only use Linux I will not be able to test it for
>>>> myself, but I can't imagine that none of the windows programmers could find
>>>> a solution for this. perhaps you should give it another try and repost the
>>>> patch to the developers list?
>>>>
>>>> thanks to all for your help
>>>> I wish you what
>>>> FloB
>>>>
>>>>
>>>> On Sat, May 29, 2010 at 4:36 AM, David Gobbi <david.gobbi at gmail.com> wrote:
>>>>>
>>>>> Hi Charl,
>>>>>
>>>>> I've looked over the patch and I have one question. What happens when
>>>>> an python exception is thrown in a python observer callback? I didn't
>>>>> see any modifications to vtkPythonCommand, so I'm guessing that the
>>>>> error will just be printed (like it is now) and not fed back to the
>>>>> original caller.
>>>>>
>>>>> David
>>>>>
>>>>>
>>>>> On Fri, May 28, 2010 at 4:43 PM, Charl Botha <c.p.botha at tudelft.nl> wrote:
>>>>> > Dear Florian and David,
>>>>> >
>>>>> > On 28 May 2010 21:07, Florian Bruckner <e0425375 at gmail.com> wrote:
>>>>> >>
>>>>> >> is there a reason why the patch was not merged into the official vtk
>>>>> >> release?
>>>>> >>
>>>>> >> i'm just wondering because that patch is fairly old and for me this
>>>>> >> seems to be a very good solution for a general problem.
>>>>> >
>>>>> > The patch has a permanent home here:
>>>>> >
>>>>> > http://code.google.com/p/devide/source/browse/trunk/johannes/patches/pyvtk_tryexcept_and_pyexceptions.diff
>>>>> >
>>>>> > Of course I think it's a good patch. :) It does the following:
>>>>> > 1. Turns all VTK errors into Python exceptions.
>>>>> > 2. Carefully releases the GIL during all calls into VTK (grabbing it
>>>>> > back for observers) so that you can successfully explicitly
>>>>> > multi-thread VTK pipelines from Python.
>>>>> > 3. Tries to trap bad_alloc.
>>>>> >
>>>>> > I've been working on this for years, but due to Windows unreachable
>>>>> > code warnings that I have not been able to solve, I've never committed
>>>>> > this to VTK (it works, just gives many warnings during compilation).
>>>>> > My own binaries all have this patch integrated (DeVIDE [1] and VTK
>>>>> > [2]).
>>>>> >
>>>>> > The current version is for 5.4.2, I'd like to update for 5.6 as soon
>>>>> > as I can figure out how to check out a clean 5.6 with git (until very
>>>>> > recently there was no tag yet, I see that it's there now!
>>>>> > http://vtk.org/gitweb?p=VTK.git;a=summary )
>>>>> >
>>>>> > I'm also considering to make a wiki page on devide.googlecode.com that
>>>>> > documents the patch.
>>>>> >
>>>>> > See you,
>>>>> > Charl
>>>>> >
>>>>> > [1] http://graphics.tudelft.nl/Projects/DeVIDE
>>>>> > [2] http://cpbotha.net/software/latest-vtk-windows-binaries/
>>>>> >
>>>>> >
>>>>> >>
>>>>> >> On Fri, May 28, 2010 at 4:07 PM, David Gobbi <david.gobbi at gmail.com>
>>>>> >> wrote:
>>>>> >>>
>>>>> >>> Hi Florian,
>>>>> >>>
>>>>> >>> I haven't seen mention of the patch here on the list, and I know
>>>>> >>> that it isn't in VTK 5.6 or in VTK devel. For my own apps, I use
>>>>> >>> VTK observers to catch reader errors.
>>>>> >>>
>>>>> >>> David
>>>>> >>>
>>>>> >>>
>>>>> >>> On Fri, May 28, 2010 at 12:52 AM, Florian Bruckner
>>>>> >>> <e0425375 at gmail.com> wrote:
>>>>> >>> > hi,
>>>>> >>> >
>>>>> >>> > I just figured out the problem that no python exceptions are raised
>>>>> >>> > if
>>>>> >>> > my reader produces an error. I use vtk-5.6.
>>>>> >>> >
>>>>> >>> > after searching the net and the mailing list I found that there are
>>>>> >>> > some
>>>>> >>> > patches available
>>>>> >>> > (turn-vtk-errors-into-python-exceptions-and-catch-bad-malloc patch)
>>>>> >>> > which should solve this problem. Unfortunately I could neither find
>>>>> >>> > such
>>>>> >>> > a patch for vtk-5.6 nor any actual posts about this topic.
>>>>> >>> >
>>>>> >>> > So should this patch allready be included in the new vtk-5.6? or
>>>>> >>> > where
>>>>> >>> > can I get it otherwise? are there any reasons why the patch is not
>>>>> >>> > included in the official release? or is there another work around
>>>>> >>> > that
>>>>> >>> > is proposed for this kind of problems?
>>>>> >>> >
>>>>> >>> > thanks
>>>>> >>> > FloB
>>>>> >>
>>>>> >>
>>>>> >> _______________________________________________
>>>>> >> Powered by www.kitware.com
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>>>>> >>
>>>>> >> Please keep messages on-topic and check the VTK FAQ at:
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>>>>> >>
>>>>> >
>>>>> >
>>>>> >
>>>>> > --
>>>>> > dr. charl p. botha :: http://graphics.tudelft.nl/CharlBotha
>>>>> > work: cpbotha at medvis.org personal: cpbotha at cpbotha.net
>>>>> >
>>>>> > See our latest papers on shape spaces, brain connectivity, shoulder
>>>>> > segmentation, human motion analysis, voxel classification and eye fat
>>>>> > deformation! http://graphics.tudelft.nl/Publications/2010
>>>>> >
>>>>
>>>>
>>> _______________________________________________
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>>
>>
>>
>> --
>> Lic. José M. Rodriguez Bacallao
>> Centro de Biofisica Medica
>> -----------------------------------------------------------------
>> Todos somos muy ignorantes, lo que ocurre es que no todos ignoramos lo mismo.
>>
>> Recuerda: El arca de Noe fue construida por aficionados, el titanic
>> por profesionales
>> -----------------------------------------------------------------
>>
>
--
Lic. José M. Rodriguez Bacallao
Centro de Biofisica Medica
-----------------------------------------------------------------
Todos somos muy ignorantes, lo que ocurre es que no todos ignoramos lo mismo.
Recuerda: El arca de Noe fue construida por aficionados, el titanic
por profesionales
-----------------------------------------------------------------
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