[keithnz]

I was active in the XP mailing group when things like SOLID got popularized, mainly by consultants. Of course the principles had been around for much longer in various forms. To me, there seemed to be a distinct difference between what some of the consultants focused on, and the books they ended up writing compared to what people who were using XP techniques and trying to leverage (determine) the best software design approaches to write actual production software. Some of the book writers / consultants were much better at actually observing (or having direct experience of) real issues and how to deal with them. But actual software design did not center around things like SOLID, those things sort of just fell out of approaching design in a particular way. I find the language too strong ( laws / principle ). Instead as you find ways to construct modular and composable software, you'll notice that things tend to have a single responsibility, you'll notice that "modules" tend to become stable and extendable through other "modules" of software. They are like side effects of good design, not things to focus on other than if a design is not really working well, it might provide an insight into why its suffering.

Which is all a polite way of saying it is mostly crap and the insight of people with real problems and who dealt with those problems is mostly ignored.