qualifiers_final_decorator error

@final decorator violations

Three violations are detected:

1. **Inheriting from a @final class** — a class decorated with @final cannot be subclassed.

2. **@final on a non-method function** — @final is only valid on methods defined inside a class body, not on module-level functions.

3. **Overriding a @final method** — a method decorated with @final in a base class cannot be overridden in a subclass.

How to handle it

Every rule is on by default — strict is the default, not a cage. You can dial qualifiers_final_decorator down per-file or per-path from your editor or pyproject.toml, or fix the code so it type-checks. See the Type System rules and the complete diagnostic reference.

Canonical URL: https://www.basilisk-python.dev/errors/qualifiers_final_decorator