Interview Question - How to programmatically screw in a lightbulb

Answer 1

Interesting idea. However, what I don't like about this is that it gives the interviewee too little idea what they are actually expected to do. If you'd ask me this question:

How would you programmatically screw in a lightbulb?

in an interview, I would have no idea what you are talking about. Add the heightened nervousness of an interview situation, and you'll have perfectly capable candidates failing at this simply because they don't know what they're supposed to do.

In my opinion, you would at least need to add

In pseudo-code reflecting the process, how would you programmatically screw in a lightbulb?

For example: .... (and then some of the code you write above)

Answer 2

None of those questions make sense from a software perspective. Perhaps you'd have better luck with something that is definitely rooted in software, even if it's too difficult to fully solve in the interview.

Alternatively, give the interviewee LightBulb and LightSocket classes with appropriate method signatures, and ask him what he would do with them. For example, how should he construct a new LightBulb? Would it be appropriate to use 'new' on it? Or should it come from a Factory of some sort? Should the LightSocket be a singleton?

Answer 3

In the perversely overengineered Lightbulb framework:

class ScrewInLightBulb extends HomeMaintenance implements CornyJokes, Lighting {

    void doIt(Light light) throws 
    WrongSizeException, FellOffChairException, CantSeeException, 
    WrongWattageException, WifeYellingAtMeException, OldBulbBrokenException {

        LightBulb lightBulb = LightBulbFactory.getInstance(LightBulbTypes.BRIGHT);
        Chair chair = ChairSingleton.getInstance();
        try {
            chair.standOn();
        } catch(BrokenChairException) {
            goto Hospital;  
        }

        LightBulb oldBulb = light.unscrewBulb();
        try {
            oldBulb.discard(TrashSingleton.getSingletonInstance());
        } catch(IllegalWasteException) {
            oldBulb.tossOutWindow();
        }

        light.screwInNewBulb(lightBulb);
        light.setState(State.ON);
        Debug.assert(light.brightness != Brightness.DARK);
    }
}

Answer 4

In pseudocode:

while( lightbulb not in socket ) {
  email [email protected] "Hey, put in a lightbulb"
  sleep 60
}

Lightbulbs are a hardware problem. Why would I, as a software developer, be asked to fix a hardware problem? :-)

Answer 5

<lightbulb onAttach="while($(this).attr('screwedIn')!=true){$(this).rotate(1/360);}"/>

Answer 6

Ahh... yes. Much like real programming, the candidate would be expected to craft a solution based on wholly inadequate requirements and a warped understanding of the capabilities of computer systems (which generally don't have manipulatable appendages).

Seriously, if the question took the form of a dialog where the candidate could ask clarifying questions, you might be able to gauge some analysis skills. Is the candidate thinking about things like socket size, wattage, voltage, etc.? Do you include a unit test to verify that the lamp lights afterwards?

If there's no interaction at all, however, I'd expect a fairly low hit rate of clever answers, and there's also the potential that an otherwise qualified candidate would leave your office believing that you're well and truly off your rocker.

Myself, I'd download a light-bulb library off codeplex and call LightBulbReplacer.ReplaceBulb();

Answer 7

A programmer would't screw in a lightbulb - it's a hardware problem. Call tech support!

Answer 8

Or code your way out of a paper bag