ActionScript 3.0 Design Patterns.pdf - VideoTutorials-bg.com

Example 1-13. QuadPets.as (continued)
}
}
}
trace("Superclass:Pet Sound");
Any class that uses the extends statement to declare a class inherits the class characteristics
it extends. The class that’s extended is the superclass (or parent). The class
that extends another class is the subclass. Both the Dog and Cat classes are subclasses
of the QuadPets class. They inherit all the superclass’ functionality. To see how that
happens, we’ll have to first create the two subclasses.
Example 1-14. Dog.as
package
{
public class Dog extends QuadPets
{
public function Dog( ):void
{
}
public function bark( ):void
{
trace("Dog class: Bow wow");
}
}
}
Example 1-15. Cat.as
package
{
public class Cat extends QuadPets
{
public function Cat( ):void
{
}
public function meow( ):void
{
trace("Cat class: Meow");
}
}
}
To see how the Dog and Cat classes inherit the operations of the superclass, the
TestPets class simply invokes the single method (makeSound) from the superclass. As
you can see from the Dog and Cat classes, no such method can be seen in their construction,
and so you can see that it must have originated in the QuadPets class.
26 | Chapter 1: Object-Oriented Programming, Design Patterns, and ActionScript 3.0