mixin.ts

export type Class = new (...args: any[]) => any;

export function DisposableMixin<Base extends Class>(base: Base) {
  return class extends base {
    isDisposed: boolean = false;
    dispose() {
      this.isDisposed = true;
    }
  };
}

export function ActivatableMixin<Base extends Class>(base: Base) {
  return class extends base {
    isActive: boolean = false;
    activate() {
      this.isActive = true;
    }
    deactivate() {
      this.isActive = false;
    }
  };
}

class Example extends DisposableMixin(ActivatableMixin(class { })) {
  member = 123;
  constructor() {
    super();
  }
}
const example: Example = new Example();