dolfin team mailing list archive

[A Navaei <axnavaei@xxxxxxxxxxxxxx>]

2009/2/13 Kent Andre <kent-and@xxxxxxxxx>:
> On fr., 2009-02-13 at 15:01 +0000, A Navaei wrote:
>> 2009/2/13 Kent Andre <kent-and@xxxxxxxxx>:
>> > On fr., 2009-02-13 at 13:12 +0000, A Navaei wrote:
>> >> his error in python:
>> >>
>> >>   File
>> >> "/usr/lib/InsightToolkit/WrapITK/lib/itkImageToDolfinFunctionPython.py",
>> >> line 273, in Convert
>> >>     return
>> >> _itkImageToDolfinFunctionPython.itkImageToDolfinFunctionID2_Convert(*args)
>> >> RuntimeError: *** Error: Unable to assign to function, missing
>> >> coefficients (user-defined function).
>> >
>> > This is caused by the following:
>>
>> Yes, I've noticed this. But why doesn't this error happen when calling
>> the sub-class from python? Why should v._vector be null when the
>> cub-class is called from c++?
>
> There are some magic that goes on in the python version of Function.
> Hake is the master of this function, so I cc him.

Johan: Why the extensions in dolfin/site-packages/function.py are not
implemented in c++ and then wrapped in python? It seems focusing some
parts of the development in the python layer has caused some stuff to
be missed in the c++ core. For reference I copy the previous
communication with Kent:

----------------------------
There are some issues with coding dolfin under c++, a code which works
with python is difficult, if not impossible, to re-produce in c++. I
tried sub-classing
dolfin::Function as itk::DolfinImageFunction:

http://code.google.com/p/wrapitk/source/browse/trunk/ExternalProjects/ItkDolfin/src/itkDolfinImageFunction.h

After wrapping in python, using wrapped itk::DolfinImageFunction works fine in
python, but the same procedure fails when implemented in c++, as
demonstrated here:

http://code.google.com/p/wrapitk/source/browse/trunk/ExternalProjects/ItkDolfin/src/itkImageToDolfinFunction.h#56

which generates this error in python:

 File "/usr/lib/InsightToolkit/WrapITK/lib/itkImageToDolfinFunctionPython.py",
line 273, in Convert
   return _itkImageToDolfinFunctionPython.itkImageToDolfinFunctionID2_Convert(*args)
RuntimeError: *** Error: Unable to assign to function, missing
coefficients (user-defined function).

Here is the python test generating the above error:

http://code.google.com/p/wrapitk/source/browse/trunk/ExternalProjects/ItkDolfin/tests/test-01.py