New CAT call
Introcution
The ECMA standard introduces a new solution to the CAT call problem. Covariant redefinition of a formal argument is only possible to an detatchable type:
class Y feature a: B g do a.f1 end end |
class A feature f (a: ANY) do end |
class B feature f (a: STRING) do end -- not valid |
class B feature f (a: ?STRING) do end -- valid