Design

What started as lighthearted iconoclasm, poking at the bear of SOLID, has developed into something more concrete and tangible. If I do not think the SOLID principles are useful these days, then what would I replace them with? Can any set of principles hold for all software? What do we even mean by principles?

“If you had to offer some principles for modern software development, which would you choose?”

At a recent Extreme Tuesday Club (XTC) virtual meet-up, we were discussing whether the SOLID principles are outdated. A while ago I gave a tongue-in-cheek talk on the topic, so ahead of the meet-up one of the organisers asked what principles I would replace SOLID with since I disagreed with them. I have been thinking about this for some time and I proposed five of my own, which form the acronym CUPID.

My friend Gojko Adzic has been running a series of BDD quizzes illustrating different ways to approach some interesting BDD situations. I noticed on Twitter that Seb Rose, another BDDer (Cucumberer?), had gently taken issue with one of Gokjo’s solutions so I thought I’d take a look at them both. Before reading on I recommend reading Gojko’s solution and Seb’s response for context.

Should examples/tests/specs/whatever be DRY (Don’t Repeat Yourself)? I’ve been thinking (and talking and arguing) about the value of test names recently and whether they are just unnecessary duplication, but that’s the subject of a future discussion. This is about the actual content of your examples. So, should your examples be DRY?

I was in a hotel in Stockholm recently and I noticed a bottle opener attached to the wall in the bathroom. There was a bilingual sign under it which got me thinking about the term “bottle opener” itself. (I was giving a talk about BDD the next day so I was already thinking about how language is used.)

It occurred to me that “bottle opener” is a great example of goal-oriented vocabulary. The device itself is actually a cap remover, and it only works on one particular design of metal cap. The reason I use it, however, is to enable me to get to the beer in the bottle. Hence “bottle opener” rather than “cap remover”.

I was lucky enough to attend the Software Architecture Workshop in Cortina recently. It was a three day workshop based around the idea of Open Spaces, which involves handing the asylum keys to the inmates and seeing what happens. I convened a session called “What’s so hard about Event-Driven Programming?” to explore the experiences of the other delegates in designing, implementing and testing asynchronous, event- or message-driven systems. I took the position that actually it was all very straightforward as long as you followed a few basic principles.