Hi Everybody, I try to be up-to-date with Pharo trends and releases. In Pharo 12, we are switching to use fluid class declaration. Its' not easy to find stuffs illustrating fluid API. I have spend many hours to browse Pharo documentation, Github repos, slides, MOOcs, books, papers finding a way to clearly explain this "new way" of declaring a class. All Pharo introduction resources and Pharo 12 videos do not use fluid class declaration but the "old" way. I also use (and let's say teach) Pharo in my OOP lectures ð If I'm not wrong, the fluid class declaration does no more explicitly deal with instance (and class) variables. Instead, it deals now with slots, tags, shared variables, traits,...At a fist look, I was understanding that slots was a dynamic way to declare instance variables. After reading some pieces of paper, and if I'm not wrong , slots are not really instance variables and shared variables are not class variables. Avoiding the old class declaration, i.e. Â Â Â Â Â Object subclass #SomeClassName instanceVariableNames: 'instaVar1 instVar2 ...' ... is there a simple way to add an instance (or class) variable? Are instance variables gone in Pharo? I assume I missed something, but what? Many thanks. Cheers, Herve