[vtkusers] Documentation for event callback return values?

[David Gobbi]

On Wed, Jun 15, 2016 at 7:51 AM, Elvis Stansvik <
elvis.stansvik at orexplore.com> wrote:

> Hi all,
>
> I noticed in QVTKRenderWindowInteractor that it returns 1 in the callback
> it sets up for DestroyTimerEvent:
>
>     def DestroyTimer(self, obj, evt):
>         self._Timer.stop()
>         return 1
>
> So I suspect callbacks for this event are expected to return something.
> But I can't find any info in the docs on which event callbacks are expected
> to return something (and what), and which are not. Is this info available
> somewhere?
>

I checked the code for the Execute command in vtkPythonCommand.cxx, and the
return value for callbacks is ignored.  So I'm not sure why this callback
returns a value.  Prabhu might remember (he wrote the function), but that
was way back in 2002.  It was probably a simple mistake due to
cut-and-paste.

If anything, a non-negative return value would indicate that the callback
had aborted, e.g. that the callback did not complete whatever action it was
meant to perform.  But obviously that's not the intent for this method.

 - David
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20160615/c115fe8a/attachment.html>