示例

在这个示例中,首先定义了一个基类和该类的扩展。基类描述了普通的蔬菜, 是否可食用及其颜色。子类 Spinach 添加了烹饪的方法和检查是否已烹饪的方法。

示例 #1 定义类

Vegetable

<?php

class Vegetable {
public
$edible;

public
$color;

public function
__construct($edible, $color = "green")
{
$this->edible = $edible;
$this->color = $color;
}

public function
isEdible()
{
return
$this->edible;
}

public function
getColor()
{
return
$this->color;
}
}

?>

Spinach

<?php

class Spinach extends Vegetable {
public
$cooked = false;

public function
__construct()
{
parent::__construct(true, "green");
}

public function
cook()
{
$this->cooked = true;
}

public function
isCooked()
{
return
$this->cooked;
}
}

?>

接下来从这些类中实例化了两个对象并打印了它们的信息,包括了他们类的继承关系。 同时也定义了一些实用函数,主要为了漂亮地打印出这些变量。

示例 #2 test_script.php

<?php

// 注册自动加载器以加载类
spl_autoload_register();

function
printProperties($obj)
{
foreach (
get_object_vars($obj) as $prop => $val) {
echo
"\t$prop = $val\n";
}
}

function
printMethods($obj)
{
$arr = get_class_methods(get_class($obj));
foreach (
$arr as $method) {
echo
"\tfunction $method()\n";
}
}

function
objectBelongsTo($obj, $class)
{
if (
is_subclass_of($obj, $class)) {
echo
"Object belongs to class " . get_class($obj);
echo
", a subclass of $class\n";
} else {
echo
"Object 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";
printProperties($veggie);

// 和 leafy 的方法
echo "\nleafy: Methods\n";
printMethods($leafy);

echo
"\nParentage:\n";
objectBelongsTo($leafy, Spinach::class);
objectBelongsTo($leafy, Vegetable::class);

?>

以上示例会输出:

veggie: CLASS Vegetable
leafy: CLASS Spinach, PARENT Vegetable

veggie: Properties
        edible = 1
        color = blue

leafy: Methods
        function __construct()
        function cook()
        function isCooked()
        function isEdible()
        function getColor()

Parentage:
Object does not belong to a subclass of Spinach
Object belongs to class Spinach, a subclass of Vegetable

一个重要的事情是需要注意在上面的示例中,对象 $leafySpinach 的实例(Vegetable 的子类)。

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