I don’t think I am an extremist. I know that code quality can never be perfect, it can always be improved (as Uncle Bob shows e.g. in CC’s Successive Refinement) and thus it is always important to find the proper level of sufficient quality. And I admit that there is code where quality doesn’t matter that much, like one-shot utilities which you use once and throw away. But when speaking about enterprise software, which will live or 5, 10, 20 years, code quality is not anything that can be sacrificed. You may gain temporary speedup by using a quick hack solution but you are thus creating a technical debt, which will be paid for several times most likely already during the development of the software and certainly during its maintenance and further development over its long life-span. Trust me, I’ve been there, I’ve seen it, I’ve paid the price and cursed the authors of the hack.
What is code quality?
To make myself clear I should explain what I mean by the term code quality:
- Proper structuring of the code
- separation, isolation and “condensation” of individual concerns so that one piece of code does one particular thing, which is not done by any other piece of code – thus if you need to change that functionality, you have exactly one place you need to touch
- short, simple methods, relatively small classes (thanks to not mixing different concerns in the same class) – for long, overly complex classes and methods are very hard to understand and modify
- minimalization of dependencies between classes and modules so that it is simpler to change any part of the code
- Readability – expressive method, class and variable names, structuring the code so that it reads as a story – during the lifetime of an enterprise project, many developers will come and go and the code will be read much more often than being written
- Tests – though not part of the code base directly, unit tests are an enabling and enforcing factor for many code quality characteristics
Regarding code quality, I really appreciate Kent Beck’s Four Simple Design Rules.
You will pay a lot for neglecting code quality
If you don’t care for code quality you will end up with spaghetti code, where different concerns (presentation, business logic, security, logging, different business requirements, …) are so much intertwined that nobody can ever separate them again. Long pieces of code doing thousand different things – the same things at many places via copy&paste programming – containing complicated, multi-level if-else statements, preferably using magic constants and mysteriously named variables, blocks of code without any clear purpose that nobody knows what they are good for but nobody dares to remove them… Changing anything in such code is highly risky because often you need to change it at many places (which you don’t know about). Trying to understand the code will take you lot of time with the likely result that your brain will burn before you manage to grasp what, why, and how the code is doing. You run a high risk of inadvertently breaking something and because you have no unit tests – and cannot create any because the code has no units, it is an organic, amorphous beast – there is nothing to notify you about the problem unless it is too late.
Of course this is worse case scenario, where quality has been neglected both in the large scale, i.e. the architectural structure of the code, and the micro-scale of individual objects and methods. Of those two the first one is worse for it makes it impossible to improve the code part by part but both of them tend to lead to further decay of the code. Developers working on it will learn the wrong habits and contribute further to the fall.
If the software is being used and further evolved during 5, 10 years, many people will try to work on it, and each of them will struggle with those problems and pay for them with time when trying to understand the code, when trying to modify the non-modular, amorphic, copy&paste code absolutely unfit for any evolvability, and finally when hunting bugs caused by those failed attempts. And the time of those people is quite expensive and it is the customer, originaly supposed to profit from the quick hack solutions, who pays the bill.
Code quality, especially on the overall structural level, is an essential property of enterprise software, which translates directly to financial losses or gains as the software is further maintained, modified and adjusted. The customer may not understand this for him invisible property and thus it is our duty as technicians to explain it and care for it. We must strive for good code quality so that the code will be able to live on without rotting over the time. The quality will never be perfect, but it must be good enough – and this is partly measurable with the various complexity metrics etc. – and we should follow the uncle Bob’s boy scoute rule of code quality: when you are working on a piece of code, return it in a better (and never worse!) state then you got it. That means that you shouldn’t hesitate to do small scale improvements when you see an opportunity for them. The result will be that the overall quality of the code will improve over the time instead of decaying, as is usually the case. The wallet of the customer will love you for that.