How to make widget take its value from the file?

Development
1

Hello dear friends, Paraview developers!

I have a custom Filter, which has some class members, X and Y. X is being passed to filter as a field of dataset in RequestDataObject, and Y is calculated based on X.

Also I have input widgets for these values X and Y, like in XML examples

			<DoubleVectorProperty
				name="X"
				command="SetX"				
				...
			</DoubleVectorProperty>

How can I make (can I?) these widgets to take the values from the filter?

Will
command=“GetX” help?

When is this command executed? Only once? After update? How to write many commands there?

Thank you very much
Mike