Unfortunately, while I really want to love Software Design for Flexibility, it's clear that Hanson and Sussman haven't really solved (or even come close to solving) the problem they have identified in the book.
The introduction to that book is brilliant at identifying just how much room software has to grow (you can find similar talks from various Strange Loop sessions Sussman has done), and is really quite inspirational for anyone seriously thinking about the future of computing.
But the rest of the book fails to provide a coherent answer to the questions that are brought up in the intro. It shows off some neat functional programming tricks, but repeatedly fails to deliver on solving the (admittedly ambitious) challenges it provides for itself.
I'm still glad I have a copy, and have re-read the first half multiple times now, but sadly it's not the book it wants to be. To be fair though, that is because we haven't come close to understanding computation enough to solve those problems.
It's a very ambitious book that falls short of it's own ambitious.
Written as the textbook for a software engineering course, it developed out of that course being taught multiple times _and_ all the code reviews which that entailed.
Previous discussions/mentions here which had a notable number of comments:
I re-wrote my current project in the course of reading it (I would read a chapter, then read through the code and where appropriate apply the relevant principle) and once I finish the current re-write (from OpenSCAD to Python) will be repeating that process to see if what I was supposed to have learned stuck/survived the re-write.
IMO it's not excellent. It's not like SICP, it's obtuse for no reason, I find it a hard slog. Flexibility is good but it seems to try to make every bit of your program flexibile and pluggable and you just need to do something eventually.
My opinion, I'd welcome others on the book; there was a small splash when it came out but not much discussion since.
I haven't read the book, but my experience is that the way to make things flexible is to make them simple as possible.
When I've used (or built) something that was built in the style like you're talking about, it's almost always wrong, and the extra complexity and stuff now makes it harder to do right. It's not surprising: unknown future requirements are unknown. Over building is trying to predict the future.
It's like someone building a shed and pouring a foundation that can work for a skyscraper. Except it turns out what we needed was a house that has a different footprint. Or maybe the skyscraper is twice the height and has a stop for the newly-built underneath. Now we have to break apart the foundation before we can even begin work on new stuff; it would have been less work if the original just used a foundation for a shed.
I think that is what the book does. Step by step introducing new requirements, by telling you about a situation, where the previous code would not be flexible enough. I am sure it doesn't state, that one should apply all of its ideas all the time, regardless of the project at hand.
I don't know about books, but I think the best approach is functional programming in a dynamic language. That could be because I'm currently an Elixir fanboy, but I think Lisps, especially Scheme or Clojure, or a functional-restricted approach in JavaScript could do it as well. I agree with parent comment that it's better to keep things as simple as possible and make the changes when necessary vs. building in all the flexibility in the beginning.
"Software Design for Flexibility: How to Avoid Programming Yourself into a Corner" by Chris Hanson and Gerald Jay Sussman
It's from 2021.