It's not rare to add components to a sum type, by example a MouseEvent
is upgraded to add the number of mouse wheel scroll knobs.
(later corrected to "product")
To do that, you can't just blindly add a new component, because existing
ctor calls will no longer link. If yesterday you had
record Foo(int x, int y) { }
then if you want to add a z, you have to:
record Foo(int x, int y, int z) {
Foo(int x, int y) { this(x,y, 0); }
}
and now old ctor sites will link.
It's exactly the same with dtors; if you add a component, you have to
explicitly provide the dtor with the old descriptor.
in my opinion, a cascade of if ... instanceof and a switch on types
should have the same constraints
It's a good intuition, but can you be specific about what constraints
you are talking about?
