PHP 5 introduces abstract classes and methods. It is not allowed to create
an instance of a class that has been defined as abstract. Any class that
contains at least one abstract method must also be abstract. Methods
defined as abstract simply declare the method's signature they cannot
define the implementation.
Eksempel 14-10. Abstract class example
<?php
abstract class AbstractClass {
/* Force Extending class to define this method */ abstract protected function getValue();
/* Common method */ public function print() { print $this->getValue(); }
}
class ConcreteClass1 extends AbstractClass {
protected function getValue() { return "ConcreteClass1"; }
}
class ConcreteClass2 extends AbstractClass {
protected function getValue() { return "ConcreteClass2"; }
}
$class1 = new ConcreteClass1; $class1->print();
$class2 = new ConcreteClass2; $class2->print(); ?>
|
|
Old code that has no user-defined classes or functions named
'abstract' should run without modifications.