Metaphysical Developer

Quality of Code

Posted in Software Development by Daniel Ribeiro on April 20, 2009

Just the other day I was skimming through a list of topics to post here that I had crafted, and just realized that several of them had a very common, yet simple, motif: improving quality of code. This can sound quite sensible and simple to a lot of people, yet its an idea as powerful as it is controversial. And when I speak of quality of code, it is important to stress that this is the code for humans, as a machine doesn’t really care about it. Setting up this theme, Martin Folwer’s statement feels quite appropriate:

Any fool can write code that a computer can understand. Good programmers write code that humans can understand.
-Martin Fowler et al, Refactoring: Improving the Design of Existing Code, 1999

This statement is almost a Quality of Code Manifesto. More precisely, it is about readability, but both concepts are very intertwined. Readability is essential to write code with good internal quality (quality as measured by the programmers). Kent Beck, on Extreme Programming Explained, also mentions how high external quality (quality as measured by the users) can’t be maintained with a low internal quality:

Temporarily sacrificing internal quality to reduce time to market in hopes that external quality won’t suffer too much is a tempting short-term play. And you can often get away with making a mess for a matter of weeks or months. Eventually, though, internal quality problems will catch up with you and make your software prohibitively expensive to maintain, or unable to reach a competitive level of external quality.

Martin Fowler explains these interactions on a article called Technical Debt. Summing it up, code with poor quality is hard to maintain, hard to change, and therefore, costs a lot more in the long run than code with a good internal quality. Not to mention that it lacks transparency, and this can go really bad even outside software programming.

Donald Knuth also made his statement about quality of code on his work with Literate Programming, which had an impact on Kent Beck’s work.

This is such an old issue, that I felt a bit insulted when I read the following (from this post): Java (the programming language) is Turing complete so no new language feature can enable us to solve a problem with Java that would be unsolvable without the language feature.

All of this sounded me absurd, since languages are tools to express code. If being Turing complete was enough, C would be all everybody needed, regardless of being a terrible language to express intention, and therefore, to make readable code. However, the author continues: Therefore any new language feature is at best a convenience to those reading and writing the code. Such features of convenience are not to be lightly dismissed, as they allow developers to increase the signal to noise ratio of our source code.

Therefore, in order to create good code, several practises, tools and concepts were created to helps or warn us: design patterns, DSLs, peer review, object orientation, functional programming, architectural patterns, agile methodologies, refactoring, pair programming, encapsulation, inversion of control, automated tests, code generation, anti-patterns, continuous integration, logic languages, fluent code….

And several of these topics are to encompass this metaphysics.

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  1. […] Quality of Code: refactorings are easier to accomplish safely when one person is not focused on actually performing […]


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