[vtk-developers] Image multiple input filters, VTK 5 vs VTK 4

[Berk Geveci]

I would have a check that compares idx to the number of existing
connections and reject if idx >= num connections. This way, it would
be impossible to create null connections.

On 4/6/06, David Gobbi <dgobbi at atamai.com> wrote:
> Brad King wrote:
> > David Gobbi wrote:
> >> I understand the concerns with SetNthInputConnection and
> >> think that the best solution would be to make it public only
> >> in the few filters that properly check for null inputs.  That
> >> would be a 100% solution for me.
> >
> > That was the intention of the method and the reason it is protected in
> > vtkAlgorithm.  Only filters that care about multiple ordered
> > connections on the same port need this anyway, and they should be able
> > to deal with NULL inputs.
> >
> > Summary of the solution:
> >
> > 1.) Add a public version of SetNthInputConnection to vtkImageBlend.
> >     It should probably be called something else and not accept the
> >     port number argument (since only port 0 supports this).
> >     Perhaps "void SetNthBlendImage(int n, vtkAlgorithmOutput*)".
> >
> > 2.) Override the SetInput methods in vtkImageBlend to map the input
> >     numbers the way the old filter treated them.  IIRC at least one
> >     was a stencil.
>
> For #1, the chosen name should be similar to AddInputConnection()
> since that's the other method that would be used to build up the inputs.
> I wouldn't want "Blend" to be part of the method name, since I'd like
> the other multiple-input filters to have the same method.  Maybe this:
>
>  ReplaceNthInputConnection(int idx, vtkAlgorithmOutput *)
>
> The connotation here is that you should only "Replace" a connection
> that has already been "Added."  It'll make people think twice before
> creating null inputs.  Any comments?
>
>  - David
>
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