interface ClockConstructor {
    new (hour: number, minute: number): ClockInterface;
}
interface ClockInterface {
    tick();
}

function createClock(ctor:ClockConstructor, hour:number, minute:number):ClockInterface{
    return new ctor(hour, minute);
}

class DigitalClock implements ClockInterface {
    constructor(h: number, m: number) { }
    tick() {
        console.log("beep beep");
    }
}
class AnalogClock implements ClockInterface {
    constructor(h: number, m: number) { }
    tick() {
        console.log("tick tock");
    }
}

let digital = createClock(DigitalClock, 12, 17);
let analog = createClock(AnalogClock, 7, 32);