His argument against inheritance seems based largely on Python's weak implementation of private attributes. No, it seems like a Python-based example of one of

His argument against inheritance seems based largely on Python's weak implementation of private attributes. No, it seems like a Python-based example of one of the well-known problems with inheritance, which applies even in languages like Java and C++ with explicit compiler-enforced visibility modifiers. Difficulty determining which class in a hierarchy is responsible for a particular member is not only a Python problem, or an "only languages without explicit public/private/protected" problem. One reason why composition is favored -- and remember, "composition over inheritance" goes back to the GoF book and earlier! -- is clearing this up. Of course, blindly "composing" is also bad, which is what this post points out.