My new job at PromptWorks, and thoughts on developer interviews

I’m excited to officially start my new job at PromptWorks next week. The slogan on their website says it all: “we are craftsmen.” If you’ve seen my Clean Code talk, you know what software craftsmanship means to me. An important aspect of it is to keep improving your skills. I’ve been working at PromptWorks on a contract basis for the past several weeks, and I can tell already that I will learn a lot from my new co-workers. They place a strong emphasis on Agile practices, quality, and working at a sustainable pace. I’ve seen enough so far to know that this isn’t just talk, and that their focus is on building long-term relationships with their clients and their staff. They’re also very involved in the local tech community. Among other things, one of them oversees the philly.rb Ruby meetup group.

They’re also supportive of me working remotely while Post to Post Links II error: No post found with slug "living-in-fukuoka-japan-this-summer-and-fall", which is very generous of them (especially for a new hire).

I interviewed with several different companies recently, and for me, the most dreadful part of interviewing is being asked to do live coding. This is sometimes done in the form of a pop-quiz, where I’m presented with some out of the ordinary coding problem, and I’m expected to write code on a whiteboard, or hack together a quick script to solve it. Other times it’s a surprise mini-project I’m expected to do on the spot. Even though I’ve been coding for close to 20 years, and I’ve had plenty of experience doing quality work faster than expected, I’m terrible at these coding exercises.

The issue for me is that they are nothing like doing real work. The only times in my life I’ve had to think up code on the spot for a surprise problem and write it on a whiteboard is in interviews. And in a real job I don’t think I’ve ever had a project dropped on me out of the blue and been asked to code up a solution in an hour or two, with severe consequences if I make a mistake or try to talk to anyone about it.

My thinking process is largely driven by understanding context (the context of the code, and the context of the business problem), and these coding exercises are usually devoid of context. I’ve also trained myself over the years to not just hack things together. I was told in one interview that, sorry, you won’t have time to write tests. Telling me to take my best practices and throw them out the window in an interview strikes me as completely backwards.

How to best interview programmers is a hotly debated topic. Some very respected people, like Joel Spolsky, swear by the whiteboard-coding approach. Others say you’re doing it wrong:

A candidate would come in, usually all dressed up in their best suit and tie, we’d sit down and have a talk. That talk was essentially like an oral exam in college. I would ask them to code algorithms for all the usual cute little CS problems and I’d get answers with wildly varying qualities. Some were shooting their pre-canned answers at me with unreasonable speed. They were prepared for exactly this kind of interview. Others would break under the “pressure”, barely able to continue the interview…

But how did the candidates we selected measure up? The truth is, we got very mixed results. Many of them were average, very few were excellent, and some were absolutely awful fits for their positions. So at best, the interview had no actual effect on the quality of people we were selecting, and I’m afraid that at worst, we may have skewed the scale in favor of the bad ones…

So what should a developer job interview look like then? Simple: eliminate the exam part of the interview altogether. Instead, ask a few open-ended questions that invite your candidates to elaborate about their programming work.

– What’s the last project you worked on at your former employer?
– Tell me about some of your favorite projects.
– What projects are you working on in your spare time?
– What online hacker communities do you participate in?
– Tell me about some (programming/technical) issues that you feel passionately about.

When I became Director of the web team at the Penn School of Medicine, I led an overhaul of how we conducted our interviews, and we adopted questions similar to these. We focused on behavior-description questions, which are actually much more revealing than you might think, if you haven’t tried them before. We also asked for interviewees to bring in a sample of their code, and we’d have them talk us through it in the interview, and answer any questions we had about it. This was an excellent and reliable way to get an understanding of their experience level and getting past shyness and nervousness. For anyone who’s done half-way decent work, they always become animated when showing off work they’re proud of.

For my interview with PromptWorks, they gave me a small project to do on my own time, to turn in a few days later, which is also a good approach. Apart from that, they also had me do a pair programming exercise, which I was worried about at first, but the focus was on getting an understanding of my thought process and overall problem-solving approach, as opposed to how fast I could tear through it, or trying to hit me with “gotcha” questions.

And they hired me, so I must have gotten something right 😉

One Comment

  1. Reply
    pat April 27, 2014

    Good luck with this job Michael. You will do a fantastic job.

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