The clearest way to express polymorphism is via an abstract base class (or interface) public abstract class Human{ … public abstract void goPee(); } This class is abstract because the goPee() method is not definable for Humans. It is only definable for the subclasses Male and Female. Also, Human is an abstract concept — You … Read more
If you think about the Greek roots of the term, it should become obvious. Poly = many: polygon = many-sided, polystyrene = many styrenes (a), polyglot = many languages, and so on. Morph = change or form: morphology = study of biological form, Morpheus = the Greek god of dreams able to take any form. … Read more
No, a List<Dog> is not a List<Animal>. Consider what you can do with a List<Animal> – you can add any animal to it… including a cat. Now, can you logically add a cat to a litter of puppies? Absolutely not. // Illegal code – because otherwise life would be Bad List<Dog> dogs = new ArrayList<Dog>(); … Read more
Here is how I understood not just what virtual functions are, but why they’re required: Let’s say you have these two classes: class Animal { public: void eat() { std::cout << “I’m eating generic food.”; } }; class Cat : public Animal { public: void eat() { std::cout << “I’m eating a rat.”; } }; … Read more
Virtual destructors are useful when you might potentially delete an instance of a derived class through a pointer to base class: class Base { // some virtual methods }; class Derived : public Base { ~Derived() { // Do some important cleanup } }; Here, you’ll notice that I didn’t declare Base’s destructor to be … Read more