I want to provide myself with a little framework that looks something like:
A = class
A1 = class (A)
A2 = class(A)
A1 and A2 are still abstract and I have to derive some Bs from either A1 or A2. A1 and A2 implement a method Foo that I want to call from A but I don’t want any B to be able to override Foo. I know I can put A, A1 and A2 into one single file and access private methods but I want to avoid it (I like small units). Tricky?