ZEND PHP 5 Certification STUDY GUIDE

116 ” Object Oriented Programming in PHP
}
$a = new a();
$b = new b();
$c = new c();
$d = new d();
$a->test(); // Outputs "a::test called"
$b->test(); // Outputs "b::test called"
$b->func(); // Outputs "a::func called"
$c->test(); // Outputs "b::test called"
$d->test(); // Outputs "b::test called"
In this script, we start by declaring a class called a. We then declare the class b, which
extends a. As you can see, this class also has a test() method, which overrides the
one declared in a, thus outputting b::test called. Note, however, that we can still
access a’s other methods—so that calling $b->func() effectively executes the function
in the a class.
Naturally, extending objects in this fashion would be very limiting, since you
would only be able to override the functionality provided by parent classes, without
any opportunity for reuse (unless you implement your methods using different
names). Luckily, parent classes can be accessed using the special parent:: namespace,
as we did for class c above; you can also access any other ancestor classes by
addressing their methods by name—like we did, for example, in class d.
Class Methods and Properties
As we mentioned earlier, classes can contain both methods and variables (properties).
Methods are declared just like traditional functions:
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
class myClass {
function myFunction() {
echo "You called myClass::myFunction";
}
}
From outside the scope of a class, its methods are called using the indirection operator
->: