[cogman10]

While inheritance can certainly work, especially in terms of UI development, the issue is when you are talking more abstract concepts. At that point, it can become really hard to figure out the right lines for what should be inherited vs composed.

In my experience, poorly composed code is simply easier to understand than code which poorly applies inheritance.

For me, inheritance is best used lightly. The obvious smell is when you end up with methods that don't apply to all the base classes. Or, said another way, when a super class it has a superset of capabilities for a base class.

A good example of this is Java's collections, which, for the most part, are quite good with their inheritance. However, because the base classes have mutable methods, it makes it a pain to deal with unmodifiable collections. Java's mistake is they should have had the default collection be unmodifiable and had sub classes which added mutation capabilities. List and MutableList, for example.