Peter Seibel - Coders at Work - Reflections on the craft of programming

Seibel:During that time did you take any classes on programming?

Fitzpatrick:Not really. It was all one or two books from the library, and then just playing around. There weren’t really forums or the Internet. At one point I got on a BBS, but the BBS didn’t really have anything on it. It wasn’t connected to the Net, so it was people playing board games.

Seibel:Did your school have AP computer science or anything?

Fitzpatrick:Well, we didn’t have AP C.S., but we had a computer programming class. There was a guy teaching it but then I would teach sort of an advanced class in the back. They still use the graphics editor and the graphics library I wrote—their final project is to make a game. I still occasionally run into that C.S. teacher—he’s a friend of my family’s and I’ll see him at my brother’s soccer games—he’ll be like, “Yep, we still use your libraries.”

I did take the AP C.S. test. It was the last year it was in Pascal before they switched to C, which was one year before they switched to Java or something like that. I didn’t know Pascal so I went to a neighboring high school that had AP C.S. and I went to some night classes, like three or four of them. Then I found a book and learned the language, and I spent most of my time building asteroids in Pascal because I had just learned trig. I was like, “Oooh, sin and cosin; these are fun. I can get thrust and stuff like that.”

Seibel:How’d you do?

Fitzpatrick:Oh, I got a five. I had to write bigint classes. Now that’s one of the interview questions I give people. “Write a class to do arbitrary, bigint manipulation with multiplication and division.” If I did it in high school on an AP test, they should be able to do it here.

Seibel:Your freshman year in college you worked at Intel during the summer. Did you also work as a programmer during high school?

Fitzpatrick:Yeah, I worked at Tektronix for a while. Before I had any official job, I got some hosting account. I got kicked off of AOL for writing bots, flooding their chat rooms, and just being annoying. I was scripting the AOL client from another Windows program. I also wrote a bot to flood their online form to send you a CD. I used every variation of my name, because I didn’t want their duplicate suppression to only send me one CD, because they had those 100 free hours, or 5,000 free hours. I submitted this form a couple thousand times and for a week or so the postman would be coming with bundles of CDs wrapped up.

My mom was like, “Damn it, Brad, you’re going to get in trouble.” I was like, “Eh—their fucking fault, right?” Then one day I get a phone call and I actually picked up the phone, which I normally didn’t, and it was someone from AOL. They were just screaming at me. “Stop sending us all these form submissions!” I’m not normally this quick and clever, but I just yelled back, “Why are you sending me all this crap? Every day the postman comes! He’s dropping off all these CDs!” They’re like, “We’re so sorry, sir. It won’t happen again.” Then I used all those and I decorated my dorm room in college with them. I actually still have them in a box in the garage. I can’t get rid of them because I just remember them being such a good decoration at one point.

After I got kicked off of AOL, I got a shell account on some local ISP. That’s basically where I learned Unix. I couldn’t run CGI scripts, but I could FTP up, so I would run Perl stuff on my desktop at home to generate my whole website and then upload it. Then I got a job at Tektronix, like a summer intern job. I knew Perl really well and I knew web stuff really well, but I had never done dynamic web stuff. This was probably ’95, ’94—the web was pretty damn new.

Then I go to work at Tektronix and on my first day they’re introducing me to stuff, and they’re like, “Here’s your computer.” It’s this big SPARCstation or something running X and Motif. And, “Here’s your browser.” It’s Netscape 2 or something—I don’t remember. And, “If you have some CGIs, they go in this directory.” I remember I got a basic hello-world CGI, like three lines working that night and I was like, “Holy shit, this is so fun.” I was at work the next day at six in the morning and just going crazy with CGI stuff.

Then I started doing dynamic web-programming stuff on my own. Maybe at that point I had found a web server for Windows that supported CGI. I finally convinced my ISP—I’d made friends with them enough, or sent enough intelligent things that they trusted me—so they said, “OK, we’ll run your CGIs but we’re going to audit them all first.” They’d skim them and toss them in their directory. So I started running this Voting Booth script where you created a topic like, “What’s your favorite movie?” and you could add things to it and vote them up. That got more and more popular. That was going on in the background for a couple of years.

Seibel:That was FreeVote?

Fitzpatrick:Yeah, that turned into FreeVote after it flooded my host. Banner ads were really popular then, or they were just getting really popular, and I kept getting more and more money from that, better contracts, more cost per click. At the height I was getting 27 cents per click of banner ads, which I think is pretty ridiculous even by today’s standards. So at the height, I was making like $25, $27 grand per month on fucking clicks on banner ads.

This was all through high school—I did this in the background all of high school. And I worked at Intel two summers, and then started doing LiveJournal my last summer, right before college. So then my first year of college, I was just selling FreeVote, which I basically sold for nothing to a friend, for like $11 grand just because I wanted to get rid of it and get rid of legal responsibility for it.

Seibel:When you got on your ISP and got to use Unix, did that change your programming much?

Fitzpatrick:Yeah. It didn’t drive me crazy. I couldn’t understand what was going on with Windows. You’ve probably seen the Windows API—there are like twenty parameters to every function and they’re all flags and half of them are zero. No clue what’s going on. And you can’t go peek underneath the covers when something’s magically not working.

Seibel:Are there big differences you can identify between your early approach to programming or programming style to the way you think about programming now?

Fitzpatrick:I went through lots of styles, object-oriented stuff, and then functional stuff, and then this weird, hybrid mix of object-oriented and functional programming. This is why I really love Perl. As ugly as the syntax is and as much historical baggage and warts as it has, it never fucks with me and tells me what style to write in. Any style you want is fine. You can make your code pretty and consistent, but there’s no language-specified style. It’s only since I’ve been at Google that I’ve stopped writing much Perl.

I’ve also done a lot of testing since LiveJournal. Once I started working with other people especially. And once I realized that code I write never fucking goes away and I’m going to be a maintainer for life. I get comments about blog posts that are almost 10 years old. “Hey, I found this code. I found a bug,” and I’m suddenly maintaining code.

I now maintain so much code, and there’s other people working with it, if there’s anything halfway clever at all, I just assume that somebody else is going to not understand some invariants I have. So basically anytime I do something clever, I make sure I have a test in there to break really loudly and to tell them that they messed up. I had to force a lot of people to write tests, mostly people who were working for me. I would write tests to guard against my own code breaking, and then once they wrote code, I was like, “Are you even sure that works? Write a test. Prove it to me.” At a certain point, people realize, “Holy crap, it does pay off,” especially maintenance costs later.