Typesafe mixin using ECMAScript 2015 mixin class and class expressions

typesafe-mixin.ts

interface Constructor<T = object> {
    new(...args: any[]): T;
}

interface Disposable {
    dispose(): void;
}

function Disposable<T extends Constructor>(Base: T): T & Constructor<Disposable> {
    return class extends Base implements Disposable {
        dispose() {
            console.log('Disposed');
        }
    };
}

interface Activatable {
    activate(): void;
}

function Activatable<T extends Constructor>(Base: T): T & Constructor<Activatable> {
    return class extends Base implements Activatable {
        activate() {
            console.log('Activated');
        }
    };
}

function isActivatable(instance: any): instance is Activatable {
    return instance && typeof instance === 'object' && 'activate' in instance;
}

class Base {
    constructor(public name: string) {
    }

    baseMethod() {
        console.log('baseMethod', this.name);
    }
}

class DisposableActivatable extends Disposable(Activatable(Base)) {
    constructor(name: string) {
        super(name);
    }
}

const instance = new DisposableActivatable('instance1');
instance.dispose();
instance.activate();
instance.baseMethod();
console.log(instance instanceof DisposableActivatable);
console.log(isActivatable(instance)); // Have to use typeguard as class expressions are anonymous
console.log(instance instanceof Base);