Decoupling vs YAGNI

Question

Do they contradict?

Decoupling is something great and quite hard to achieve. However in most of the applications we don't really need it, so I can design highly coupled applications and it almost will not change anything other than obvious side effects such as "you can not separate components", "unit testing is pain in the arse" etc.

What do you think? Do you always try to decouple and deal with the overhead?

Answer 1

Well, YAGNI is little more than a bogus simplistic phrase people throw around. Decoupling, however, is a fairly well understood concept. YAGNI seems to imply that one is some sort of psychic. It's just programming by cliche, which is never a good idea. To be honest, there is a case to be made that YAGNI is probably not related to decoupling at all. Coupling is typically "quicker" and "who knows if you are you are going to need a decoupled solution; you aren't gonna change X component anyway!"

Answer 2

I (almost) always decouple. Every time I did this I found it useful, and (almost) every time I didn't I had to do it later. I've also found it a good way to decrease the number of bugs.

Answer 3

I'd say they don't. Decoupling is about reducing unnecessary dependencies within code and tightening up accesses through clean, well-defined interfaces. "You ain't gonna need it" is a useful principle which generally advises against over-extensibility and overly broad architecture of a solution where there's no obvious and current use case.

The practical upshot of these is that you have a system where it's much easier to refactor and maintain individual components without inadvertently causing a ripple effect across the entire application, and where there are no unnecessarily complicated aspects to the design - it's as simple as is required to meet the current requirements.