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Dokumen ini menggunakan Manual laman web PHP Cina Lepaskan
在这个例子中,我们首先定义了一个基类和该类的扩展。 这个基类描述了普通的蔬菜,关于它是否可食用及其颜色。 子类 Spinach 添加了烹饪的方法和另一个检查是否已烹饪的方法。
Example #1 classes.inc
<?php
// base class with member properties and methods
class Vegetable {
var $edible ;
var $color ;
function Vegetable ( $edible , $color = "green" )
{
$this -> edible = $edible ;
$this -> color = $color ;
}
function is_edible ()
{
return $this -> edible ;
}
function what_color ()
{
return $this -> color ;
}
} // end of class Vegetable
// extends the base class
class Spinach extends Vegetable {
var $cooked = false ;
function Spinach ()
{
$this -> Vegetable ( true , "green" );
}
function cook_it ()
{
$this -> cooked = true ;
}
function is_cooked ()
{
return $this -> cooked ;
}
} // end of class Spinach
?>
接下来我们从这些类中实例化了两个对象,并打印了他们的信息,包括了他们类的继承关系。 同时我们也定了一些实用函数,主要为了漂亮地打印出这些变量。
Example #2 test_script.php
<pre>
<?php
include "classes.inc" ;
// 实用函数
function print_vars ( $obj )
{
foreach ( get_object_vars ( $obj ) as $prop => $val ) {
echo "\t $prop = $val \n" ;
}
}
function print_methods ( $obj )
{
$arr = get_class_methods ( get_class ( $obj ));
foreach ( $arr as $method ) {
echo "\tfunction $method ()\n" ;
}
}
function class_parentage ( $obj , $class )
{
if ( is_subclass_of ( $GLOBALS [ $obj ], $class )) {
echo "Object $obj belongs to class " . get_class ($ $obj );
echo " a subclass of $class \n" ;
} else {
echo "Object $obj does not belong to a subclass of $class \n" ;
}
}
// 实例化 2 对象
$veggie = new Vegetable ( true , "blue" );
$leafy = new Spinach ();
// 打印这些对象的信息
echo "veggie: CLASS " . get_class ( $veggie ) . "\n" ;
echo "leafy: CLASS " . get_class ( $leafy );
echo ", PARENT " . get_parent_class ( $leafy ) . "\n" ;
// 显示蔬菜的属性
echo "\nveggie: Properties\n" ;
print_vars ( $veggie );
// and leafy methods
echo "\nleafy: Methods\n" ;
print_methods ( $leafy );
echo "\nParentage:\n" ;
class_parentage ( "leafy" , "Spinach" );
class_parentage ( "leafy" , "Vegetable" );
?>
</pre>
一个重要的东西是注意在上面的例子中,对象 $leafy 是 Spinach 的实例(Vegetable 的子类),另外脚本的最后部分会输出以下信息:
[...] Parentage: Object leafy does not belong to a subclass of Spinach Object leafy belongs to class spinach a subclass of Vegetable