A hierarchy of project needs

A few weeks ago, I traded stories with a fellow software developer when he told me this little gem: A developer programs a web shop that looks pretty and runs smooth. But as soon as you place multiple items in the shopping cart, you’ll inevitably end up with an amount of XX.999999999998 euros (or whatever currency you want). When asked why the shopping cart “computes the wrong amounts”, the developer answered that the amount is correct and that’s just the way a floating point number behaves. He didn’t see a problem with the functionality. My immediate answer: “Wow, that’s very low on the Maslow pyramid”. We both understood, but since then, I tried to come up with a Maslow-like pyramid that would explain my sentence to a larger crowd. So here is how my attempt has grown so far.

Maslow’s hierarchy of needs640px-Maslow's_Hierarchy_of_Needs.svg

Abraham Maslow was an american psychologist that studied mental health and human potential. He invented an hierarchy of human needs that is also known as Maslow’s pyramid. On a side note, he also pointed out the human tendency to over-apply known tools. His pyramid has five stages (IT people would call them layers) of human needs that begin with the very basic ones (e.g. air, water) and scales to the abstracts like morality and creativity. If something is “low on the pyramid”, then it can be seen as granted by priviledged people. Most of us never think about our air supply requirements. Everything “high on the pyramid” can be seen as “expendable” in times of crisis. Morality will be forgotten as soon as we seriously lack water.

A hierarchy of project needs

My immediate answer to the story in the introduction suggested that I think an equivalent pyramid exists for the needs of a software development project. And a quick research on the internet reveals that I’m not the only one with that idea. For example, Scott Hanselman blogged about it in 2012, and Francis Shanahan came up with an extended version in 2009. Both adaptions are reasonable and stand on their own – I don’t want to invalidate or change them. Instead, I publish my attempt as an addition to the discussion, if there is any.

Here is my five-layered pyramid of project needs:

project maslovLayer 0: Executable

Let’s face it: If your project doesn’t compile or crashes right after being started, it isn’t much worth. And just because it runs on your machine doesn’t make it any more useful to others. So the most basic need a project has is to be executable on the target machine. This includes some form of correctness – if your program doesn’t perform the right operations, it can run indefinitely and not provide any value. Please note that the program doesn’t have to be bug-free or tested to be useful. It just has to adhere to the intended use case. In our introduction story, the web shop looks pretty and runs smoothly. It certainly is “Executable”.

Layer 1: Abstraction

This is where I placed the mishap in the introduction story. Every project needs some form of abstraction or separation between the internal representation of data and functionality and the external presentation to the user. This is probably trivial to most of you, but I’ve seen way to much code that uses external presentations (e.g. strings from the GUI) to make important decisions and others have, too. A key rule is “once data is formatted, it is eternally lost and unavailable to computing / data processing“. The rule for the other way is that you should never present data without proper (human-readable) formatting. The amount of work you save by not pretty-printing (formatting is just the formal term for adding syntactic sugar to make the data edible for humans) is largely offset by the amount of work your users will have to invest to decipher the output.

Layer 2: Architecture

You can call it design, architecture or whatever you like, any reasonably large code base needs some kind of structuring that prevents it from imploding. A whole theory of patterns was invented to keep code aerated enough to prevent it from decomposing to compost. And we all know what compost code looks and smells like. Applying architecture to your code keeps it maintainable and refactorable and in outstanding cases even modularizable. This is the layer where most projects fail on the long run. Even if at first there was a design, it gets watered down with every modification. Good principles to counter this effect are the “no broken windows” approach and the boy scout rule.

Layer 3: Verification

There is a moment in programming when you hand your code over to the next developer. Usually, this moment is called “commit” (if you don’t use version control, have a good look at Scott Hanselman’s lowest pyramid layer!). Oftentimes, the next developer is future you – and you have no clue what past you thought when he wrote that crap. You can’t even distinguish between features and bugs. That’s why your project wants verification. It’s not utmost important if you verify your code with unit tests, integration tests, acceptance tests, contracts or all of them together. It’s important that your code is accompanied by automated guardian angels that catch the most dangerous accidental modifications and help to point out the bugs among the features. Automated verification tells future you that whatever past you wanted to build, it’s still intact. This layer is the life insurance for functionality as much as the architecture layer was for code.

Layer 4: Style

Every program in the world can still do its job properly even if we would eliminate everything “stylish” in their codebase. Style is the most human-centered need in the pyramid. No machine or compiler has yet developed aesthetic likings. Scott Hanselman called this layer “bragging rights”, another thing computers don’t care about. This is the level where most bickering among developers takes place, but it’s also the level that can most easily be ignored without sacrificing critical project needs. Or, to put it bluntly: Your project most likely doesn’t care half as much about style as you do.

Where to go from here?

My most important message with the hierarchy of project needs is that we often focus on the higher needs and take the lower ones too much for granted. If your code lacks in the fundamental layers, the damage is much greater in terms of project value. A stylistic displeasing code will hurt the next developer, but a code lacking abstraction will hurt every user of your software, as exemplified by the story in the introduction. As we developers should be the advocates of our project’s needs, we have to think more in regard of its benefit than our personal self-actualization. But the required traits to do so properly aren’t even on the original Maslow’s pyramid, so it’s a big challenge for any of us.

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