Page 212 - Beginning PHP 5.3

Part II: Learning the Language
case Car::STATION_WAGON:
echo “station wagon”;
break;
case Car::SUV:
echo “SUV”;
break;

}
In this example, the Car class contains three class constants — HATCHBACK , STATION_WAGON , and SUV —

that are assigned the values 1 , 2 , and 3 , respectively. These constants are then used when setting and
reading the $type property of the $myCar object.

Working with Methods

Up to this point, the classes and objects you ’ ve created have mostly consisted of properties. As such,
they ’ re not really much use, except as glorified associative arrays. It ’ s when you start adding methods to
classes that they become truly powerful. An object then becomes a nicely encapsulated chunk of
functionality, containing both data and the methods to work on that data.

As mentioned earlier, a method is much like a function, except that it ’ s tied to a specific class.

Method Visibility

Earlier in the chapter you learned that a property can have three visibility levels: public, private, and
protected.

The same is true of methods. All methods can be called by other methods within the same class. If a
method is declared public, any code outside the class definition can also potentially call the method.
However, if a method is declared private, only other methods within the same class can call it. Finally, a
protected method can be called by other methods in the class, or in a class that inherits from the class.

Creating a Method
To add a method to a class, use the public , private , or protected keyword, then the function
keyword, followed by the method name, followed by parentheses. You then include the method ’ s code
within curly braces:

class MyClass {

public function aMethod() {
// (do stuff here)
}

}

You can optionally leave out the public , private , or protected keyword. If you do this, public
is assumed.

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