More Pythonic VTK wrapping

[berk.geveci]

@cory.quammen

If you implemented this in __getattr__ it shouldn’t require a change in VTK itself. Let’s say instead of invoking execute() you simply access a output attribute. __getattr__ could perform the update on the pipeline when it the attribute output is requested and give you the result. The implementation would, I suspect, be very similar to the implementation of an execute() function. It’s mainly a syntactic preference in my view. The main advantage of an attribute is it is perhaps easier to name - you don’t have to find a verb that also indicates a noun is returned.

This is still a behavior change. Given how we create properties, I would expect .output to call GetOutput() on the algorithm, which does not execute. This is the current behavior.

@cory.quammen

That’s a good point about multiple outputs. How would this be handled with either an execute() or a output attribute? Return a tuple of VTK objects?

I did not think of returning a tuple of data objects. That’s doable. This currently returns the 2nd output:

select_ports(alg, 1).execute()

but if you want the other input after executing, you have to do:

alg.GetOutputDataObject(0)

Because of the way Python properties work, we cannot do:

alg.output(0)

We can implement that as a custom function if requested though.