> I'd argue some amount of "co-recursion" is to be expected: after all the point of the child class is to reuse logic of the parent
That's the point: You can reuse code without paying that price of inheritance. You DON'T have to expect co-recursion or shared state just for "code-reuse".
And, I think, is the key point: Behavior inheritance is NOT a good technique for code-reuse... Type-inheritance, however, IS good for abstraction, for defining boundaries, to enable polymorphism.
> I'd say this is a fact of life for all pieces of code which are reused more than once
But you want to minimize that complexity. If you call a pure function, you know it only depends on its arguments... done. If you can a method on a mutable object, you have to read its implementation line-by-line, you have to navigate a web of possibly polymorphic calls which may even modify shared state.
> This is another reason why low coupling high cohesion is so important
exactly. Now, I would phrase it the other way around though: "... low coupling high cohesion is so important..." that's the reason why using inheritance of implementation for code-reuse is often a bad idea.
That's the point: You can reuse code without paying that price of inheritance. You DON'T have to expect co-recursion or shared state just for "code-reuse".
And, I think, is the key point: Behavior inheritance is NOT a good technique for code-reuse... Type-inheritance, however, IS good for abstraction, for defining boundaries, to enable polymorphism.
> I'd say this is a fact of life for all pieces of code which are reused more than once
But you want to minimize that complexity. If you call a pure function, you know it only depends on its arguments... done. If you can a method on a mutable object, you have to read its implementation line-by-line, you have to navigate a web of possibly polymorphic calls which may even modify shared state.
> This is another reason why low coupling high cohesion is so important
exactly. Now, I would phrase it the other way around though: "... low coupling high cohesion is so important..." that's the reason why using inheritance of implementation for code-reuse is often a bad idea.