immutable top-level constant

Immutable const immutable

Used to annotate a class C. Indicates that C and all subtypes of C must be immutable.

A class is immutable if all of the instance fields of the class, whether defined directly or inherited, are final.

Tools, such as the analyzer, can provide feedback if

the annotation is associated with anything other than a class, or
a class that has this annotation or extends, implements or mixes in a class that has this annotation is not immutable.

Implementation

const Immutable immutable = Immutable();