I’d also add that live systems like Smalltalk avoid a lot of the fragility and dynamism of inheritance by the way the browsers show all the currently active ext

I’d also add that live systems like Smalltalk avoid a lot of the fragility and dynamism of inheritance by the way the browsers show all the currently active extensions to the class, and all the current subclasses in a fairly compact view. It’s a lot easier to find and modify affected child classes in this way than it is with “code in files” systems. Also, the way CLOS does inheritance avoids a lot of the drawbacks too by decoupling classes and inheritance from behavior.