PHP中__get()方法详解
PHP中把以两个下划线__开头的方法称为魔术方法(Magic methods)，这些方法在PHP中充当了举足轻重的作用。
相关：
PHP中__get()，获得一个类的成员变量时调用
在 php 面向对象编程中，类的成员属性被设定为 private 后，如果我们试图在外面调用它则会出现“不能访问某个私有属性”的错误。那么为了解决这个问题，我们可以使用魔术方法 __get()。
魔术方法__get()的作用
在程序运行过程中，通过它可以在对象的外部获取私有成员属性的值。
我们通过下面的 __get() 的实例来更进一步的连接它吧：
<?php
class Person
{
private $name;
private $age;
function __construct($name="", $age=1)
{
$this->name = $name;
$this->age = $age;
}
/**
* 在类中添加__get()方法，在直接获取属性值时自动调用一次，以属性名作为参数传入并处理
* @param $propertyName
*
* @return int
*/
public function __get($propertyName)
{
if ($propertyName == "age") {
if ($this->age > 30) {
return $this->age - 10;
} else {
return $this->$propertyName;
}
} else {
return $this->$propertyName;
}
}
}
$Person = new Person("小明", 60); // 通过Person类实例化的对象，并通过构造方法为属性赋初值
echo "姓名：" . $Person->name . "<br>"; // 直接访问私有属性name，自动调用了__get()方法可以间接获取
echo "年龄：" . $Person->age . "<br>"; // 自动调用了__get()方法，根据对象本身的情况会返回不同的值运行结果：
姓名：小明 年龄：50
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