I would like to add a parameter named initialPosx
that I can use in this manner:
a = box
a.initialPosx = n
Is there any way?
Read Scripted Custom Attributes and Scripted Plug-in Clauses topics. In your case, a trivial example would be:
a = Box()
attr = attributes attr (parameters main (initialPosX type:#point3))
custAttributes.add a attr
a.initialPosX = [5, 10, 0]