alt Hacker NewsIn my experience, the answer is always "It Depends." That's about the only thing that I can hang "always" on.
It really depends on the exact type of code we're working with, and what our objectives are.
In my case, I often use object inheritance. It's a damn cheap way to DRY. However, when people hear "inheritance," they often think "polymorphism." There's a really big difference between the two, but popular culture has jammed them into one ball, and it's not worth the agita, to try to explain the difference.
But if you are doing optimization, long stacks can be your enemy, and inheritance tends to have long, windy stacks.
In these cases, the copy/pasta method may well be the best approach.
Like I said, "It Depends."
> In my case, I often use object inheritance. It's a damn cheap way to DRY. However, when people hear "inheritance," they often think "polymorphism." There's a really big difference between the two, but popular culture has jammed them into one ball, and it's not worth the agita, to try to explain the difference.
I agree that we should think of inheritance and polymorphism separately. If we want to express this intent in object-oriented code, how can we use inheritance to deduplicate code, while preventing misuse of the resulting object hierarchy i.e. the use of base classes in a polymorphic context?
In C++, IIRC private inheritance would do the trick (you cannot static_cast DerivedWidget * to BaseWidget * if DerivedWidget : private BaseWidget), but most OO languages don't support private inheritance. It's also not possible, as far as I know, to "lock down" BaseWidget * so it cannot be used as a base class pointer from any derived class: instead, you have to apply the private inheritance to every derived class to enforce this rule.
Another approach is to use has-a instead of is-a: i.e. instead store a BaseWidget object as a member of DerivedWidget. This allows for re-use without supporting polymorphism.