Runtime virtual override

Context: Runtime polymorphism (dynamic dispatch) allows a derived class to provide a specific implementation of a method defined in the base class using virtual and override.

Example

public class Animal
{
    public virtual void Speak() => Console.WriteLine("?");
}
public class Dog : Animal
{
    public override void Speak() => Console.WriteLine("Woof");
}
public class Cat : Animal
{
    public override void Speak() => Console.WriteLine("Meow");
}

Animal a1 = new Dog();
Animal a2 = new Cat();
a1.Speak(); // Woof
a2.Speak(); // Meow

How It Works

The runtime determines the actual type of the object and calls the most derived override.

Benefits

• Open/Closed Principle: add new types without changing existing code.
• Base class references can work with any derived class.