[vtkusers] Status of VTK Python 3 wrapper support

[David Gobbi]

On Thu, Jul 31, 2014 at 6:44 AM, diego0020 <da.angulo39 at uniandes.edu.co> wrote:
>
> But I am also looking forward to this. Is there anything we could do to push
> support for python 3 forward?

There has been some discussion about converting all of the python
tests and examples, which is a part of the process where extra
manpower would be a big asset.  I imagine that the conversion will
go something like this:

1) Someone will run 2to3 on all the python code, and then make
sure that it can be byte-compiled with python3 (it will be too early
at this stage to actually run the code, but making sure that it
byte-compiles will be a good first step).

2) Lots of people will then pick through the code to fix conversion
errors and to make sure that the code actually looks like good
python3 code.

3) Finally, someone will add some CMake magic to VTK so that if VTK
is built against python2, cmake will run 3to2 on all of these new python3
files and put the equivalent python2 code into the VTK build
directory.  This is the magic that is needed to make sure that VTK
will be able to support both python2 and python3.

So any assistance with the above process would be a big help.  In
particular, it would be very useful if someone could verify that item
(3) is even feasible: in the end it might be necessary to have hand-
written python2 and python3 exist side-by-side instead of using
automatic conversion.  It _should_ be feasible, since the VTK
tests used automated tcl-to-python conversion for many years,
and python3 to python2 should be much easier than tcl to python.

 - David