On code-craft, and writing code for other programmers to use

The New Yorker this week has a profile of Google programmer pair Jeff Dean and Sanjay Ghemawat — if the annoying phrase “super star programmer” applies to anyone it’s probably these guys, who among other things conceived and wrote the original Google Map Reduce implementation–  that includes some comments I find unusually insightful about some aspects of the craft of writing code. I was going to say “for a popular press piece”, but really even programmers talking to each other don’t talk about this sort of thing much. I recommend the article, but was especially struck by this passage:

At M.I.T., [Sanjay’s] graduate adviser was Barbara Liskov, an influential computer scientist who studied, among other things, the management of complex code bases. In her view, the best code is like a good piece of writing. It needs a carefully realized structure; every word should do work. Programming this way requires empathy with readers. It also means seeing code not just as a means to an end but as an artifact in itself. “The thing I think he is best at is designing systems,” Craig Silverstein said. “If you’re just looking at a file of code Sanjay wrote, it’s beautiful in the way that a well-proportioned sculpture is beautiful.”

…“Some people,” Silverstein said, “their code’s too loose. One screen of code has very little information on it. You’re always scrolling back and forth to figure out what’s going on.” Others write code that’s too dense: “You look at it, you’re, like, ‘Ugh. I’m not looking forward to reading this.’ Sanjay has somehow split the middle. You look at his code and you’re, like, ‘O.K., I can figure this out,’ and, still, you get a lot on a single page.” Silverstein continued, “Whenever I want to add new functionality to Sanjay’s code, it seems like the hooks are already there. I feel like Salieri. I understand the greatness. I don’t understand how it’s done.”

I aspire to write code like this, it’s a large part of what motivates me and challenges me.

I think it’s something that (at least for most of us, I don’t know about Dean and Ghemawat), can only be approached and achieved with practice — meaning both time and intention. But I think many of the environments that most working programmers work in are not conducive to this practice, and in some cases are actively hostile to it.  I’m not sure what to think or do about that.

It is most important when designing code for re-use, when designing libraries to be used in many contexts and by many people.  If you are only writing code for a particular business “seeing code not just as a means to an end but as an artifact in itself” may not be what’s called for.  It really is a means to an end of the business purposes. Spending too much time on “the artifact itself”, I think, has a lot of overlap with what is often derisively called “bike-shedding”.  But when creating an artifact that is intended to be used by lots of other programmers in lots of other contexts to build things to meet their business purposes — say, a Rails… or a samvera — “empathy with readers” (which is very well-said, and very related to:) and creating an artifact where “it seems like the hooks are already there” are pretty much indispensable to creating something successful at increasing the efficiency and success of those developers using the code.

It’s also not easy even if it is your intention, but without the intention, it’s highly unlikely to happen by accident. In my experience TDD can (in some contexts) actually be helpful to accomplishing it — but only if you have the intention, if you start from developer use-cases, and if you do the “refactor” step of “red-green-refactor”.  Just “getting the tests to pass” isn’t gonna do it. (And from the profile, I suspect Dean and Ghemawat may not write tests at all — TDD is neither necessary nor sufficient).  That empathy part is probably necessary — understanding what other programmers are going to want to do with your code, how they are going to come to it, and putting yourself in their place, so you can write code that anticipates their needs.

I’m not sure what to do with any of this, but I was struck by the well-written description of what motivates me in one aspect of my programming work.

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