Friday, June 19, 2009

Cargo Cult Engineering

Process-oriented development achieves its effectiveness through skillful planning, use of carefully defined processes, efficient use of available time, and skillfull application of software engineering best practices. - Steve McConnell
I'll come back to that quote eventually, but today's post is on cargo cults.

In my experience, engineering teams succeed because there's one or two engineers on the project that are smart, hard-working self-starters, but most importantly follow sound software engineering principles and are capable of taking stepping back and getting the big picture.

Smart, Hard-Working, Self Starters

There's ways of assessing this stuff. Personally, I think gradations of these attributes are mostly worthless. Programmers of average intelligence won't be able to tackle huge problems, or get a lot of features done, but having a smart but "unwise" (using that word as a catchall for what I'll describe in the sections below) engineer is worse than having an average-intellect but wise engineer.

Hard-working is good. But I think easy to assess. And if they don't work hard once they're in place, you need to fire them. If you can't fire them, because, say, you're in France, then that sucks. Your next job will be to get them to quit. Try transferring them to the Siberian Office.

Self Starters are handy, but again I don't think it's at the top of the list. A semi-smart, hard-working, self-starting programmer that insists on overengineering everything, following a fancy & convoluted development methodology, and is unable to assess the importance (ie context) of the parts that he is working on will build lots of great code -- that won't help your product ship or keep customers happy.

What's your goal? Are you capable of assessing context? As a manager, you want programmers that help your bottom line. That means quality code, but it also means code that you need, and code that makes your clients happy. Happy clients are more important than pretty code.

The Big Picture

Whether it's figuring out how one method fits into a class, one class into a module, one module into a project, one control into a web form, a folder or set of files into a hierarchy, one product feature into the next release, themselves into the company, their company into the industry, the product into the market, etc etc -- good engineers are capable of taking a step back and assessing context.

Bad engineers do cargo cult programming. They see the artifacts of good engineers, but they don't understand the principles behind it.

Sound Engineering Principles

Lists are popular. "7 Habit of Highly Effective People", "Top 10 Ways to Ship Better Software," the lists of core rules in methodologies, and the very frequent "Five Ways to Fit into Your Swim Suit for Summer" type stuff.

Lists are easy to make. Just observe for a little while. Pretty much anyone can make lists.

But lists aren't principles. Principles are difficult to apply. They're easy to state, but the whole trick with principles is that they must take context into consideration. Principles must also exist in a hierarchy; for each principle, there must be an antecedent principle that sets boundaries. The antecedent says why a principle is important, gives a guideline for the boundaries of the principle (where it makes sense and where it doesn't), and establishes a benchmark by which to judge the execution of a principle.

Take choosing good names for local variable. This isn't just one floating point out of hundred of practices that make for good software engineering. The list-maker will take this point and stick it into his six-page bulleted list of "Best Practices."

As a principle, one chooses good names because it aids in human parsing of code. Let's chase the antecedent principles here. Human parsing of code is important because it makes maintenance (extension and debugging) easier. Maintenance happens -- so why is it important to make it easier? Because it increases the quality of software and reduces the cost of development. Why are those things important? Why are they important on this product? The answers for quality and cost vary from project to project, and I could answer them in the abstract, but how you answer this question is what settles the boundaries of the principle.

Cargo Cults

Cargo cults mimicked the habits that they saw American military men executing. They thought that the motions themselves were what caused the airplanes to land, and the cargo to show up on the beach. Likewise, the actions that McConnell outlines in that quote above -- skillful planning, use of carefully defined processes, efficient use of available time, and skillfull application of software engineering best practices -- are habits. These are good habits, but I don't think they capture the important traits at all.

Specifically, "use of carefully defined processes" implies that browsing to some Six Sigma website and then handing down the printouts to your engineering team is sufficient for project success. That's just mimicking the habits of successful developers; it's not good engineering.

1 comment:

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