I think part of the problem isn’t just bad hierarchies, it is that they are so hard to fix.

Bad OOP code gets its fingers everywhere, and tearing out a bad hierarchy can be downright impossible.

Lots of people equate OOP with inheritance, and I think that does a disservice to OOP code style in general. The original definitions of OOP had nothing to do with inheritance at all and this relationship was only popularized by a few languages (which others then copied due to aggressive marketing).

IMO the more important parts of OOP that are still useful are encapsulation and message passing which can be done in languages without inheritance.

I would caution against throwing out a paradigm before of one aspect of of that languages added onto it after the fact.

There are some infamous cases of OOP abuse in the 7 digit LOC embedded system codebase I work in. I have known several developers that created these sorts of overly-engineered inheritance hierarchies seemingly just for their own sake. It's awful, and it's even worse when the original author leaves the company and leaves these sorts of unmaintainable blocs in our applications.

But I think there are definitely places where OOP is not only beneficial but just the correct solution for a part of the application. GUI for instance--all the various widget types and how they plug in to the UI system to handle mouse events and get drawn in the correct Z-order--it's very intuitive. Of course you will find a subclass of a subclass of a subclass of Button every once in a while, and in these cases I do look for opportunities to use composition over inheritance.

By the way - can we talk about the author's weird definition of composition? I've always defined composition as a class with a "has-a" relationship with other classes. But this author still defines it as classes with a "is-a" relationship to other classes, or in this case a single "generation" of inheritance. That seems bizarre to me, especially when they give this example:

In composition, this is a simple task: go to Dog class, add getTreat call in between eating and pooping. Done. 💪

And yet, their example of a Dog class following composition literally inherits from the Animal interface and does not have a point in which Dog can, internally, insert this getTreat() call:

class Dog implements Animal { doStuff() { consumeEnergy() println("woof") rest() } }

Lol... anyway, I like the sentiment of the article but I lean much farther toward just picking the correct tool for the job. Inheritance can still be the right solution in many cases and blaming a paradigm for code readability problems doesn't seem as apt as, say, realizing that even in codebases where every commit has to be reviewed, at the end of the day you still have to ship product and there is never time to keep all code in perfect order, especially in large legacy systems*.

• note this may not apply to some open source projects or other projects where True Idealism can be/is exercised