exercise programming style

Exercises in Programming Style, stacking things up

Last week, we had our first taste of Exercises in Programming Style. Remember, the goal is to write a simple program, but to comply with some constraints. The previous constraint was that there was only a single variable available, an array. With a statically-typed language such as Kotlin, it required a lot of casting variables to their correct types before using them. This week, the constraint is as radical, but different. Instead of a single array, we have two data structures available: a hash

exercise programming style

Introducing Exercises in Programming Style

Recently, my colleague Bertrand lent me a copy of the book Exercises in Programming Style by Cristina Videira Lopes. Among all the books that sit on my reading pile, I decided to put it on top, and started reading right away. Currently reading Exercises in Programming Style by @cristalopes - and doing the exercices in #Kotlin. IMHO, it's one of the best (if not the best) book on programming I've read so far! I'll probably blog about it.Thanks @bertrand_cachet for the pointer—

Docker optimization Gemfile npm

Layering your Docker images with dependencies

Since already some years, this site uses the Jekyll static site generator. Generating the complete site takes about 15 minutes. Some time ago, I decided to setup Gulp to minimize HTML in order to speed up page view for readers. This change added about 10 minutes to the build time, for a total of ~25 minutes, which is a long time…​ too long. I wanted to decrease the build time, so I decided to play around. The initial state A Docker image is used to build the site. The image is bas

testing assertion library software craftmanship

A comparison of assertion libraries

I was not a fan of assertions libraries at first. Whether assertions provided by the testing frameworks were enough is debatable. But those libraries provides the way to write custom assertions closer to the business language. While the intention is commendable, I always thought this path was a slippery slope. If one starts writing such custom assertions, then they need to be tested obviously. And then, when will it stop? However, there’s no denying assertion libraries make writing assert

deduplication API

Deduplication trick in legacy code

It might happen that you need to deduplicate a list of items…​ coming from legacy code. The class - let’s call it LegacyObject has already implementations for equals() and hashCode(). It’s not possible to change the implementation, for fear of breaking the running code. And unfortunately, the Java API doesn’t offer a distinctBy() feature. In that case, a cheap trick is to create a wrapper class around LegacyObject, with the desired implementation: public class L

Kotlin software design UML

Options for managing derived attributes in Kotlin

A derived attribute is an attribute computed from other attributes e.g.: The fullName is aggregated from the first, middle and last nameThe age is computed from the birthdateetc. Kotlin offers different options to manage such derived attributes. Let’s browse through them. Inline field initialization The simplest way to manage derived attributes is to declare a property, and compound its declaration with its initialization: class Person(val firstName: String, val middle