[namelosw]

I too disdainful SOLID. I appreciate this finally has been pointed out. Principles are in fact moral high grounds, without telling you what to do.

For example, you need to resolve the expression problem[0] in Java, with Open-Closed principle compliant. Then the answer could be Java code like in this article[1] (the technique is Object Algebra).

However the moral for me is, if I'm using Haskell or Ruby, when expressing Open-Closed idea is simple, I would use it. If I'm using Java, just forget the principle. I would just express the business, and change the code if I need to add new types or operations. Because the principle is written the code is not understandable to other people, just like design pattern abused codebases.

Another thing is Liskov Substitution Principle. I found most of the books cover this idea don't even mention how to judge if an object is LSP compliant. Every people I know talk about the principle haven't heard of covariant and contravariant, and didn't realize almost all of the mutable data type inheritance are in fact not LSP compliant.

[0] https://en.wikipedia.org/wiki/Expression_problem [1] https://koerbitz.me/posts/Solving-the-Expression-Problem-in-...