详解php的魔术方法__get()和__set()使用介绍_PHP教程
先看看php官方文档的解释:
__set() is run when writing data to inaccessible properties.
__get() is utilized for reading data from inaccessible properties.
究竟用中文怎么翻译呢?
inaccessible :n. 难达到;难接近;无法理解。
有代码有真相:
error_reporting(E_ALL);
class stu{
private $a;
private $b = 0;
public $c;
public $d = 0;
//这里的 private 可以用 protected public 替代
private function __get($name) {
return 123;
}
//这里的 private 也可以用 protected public 替代
private function __set($name, $value) {
echo "This is set function";
}
}
$s = new stu();
var_dump($s->a); //output: 123
var_dump($s->b); //output: 123
var_dump($s->c); //output: null
var_dump($s->d); //output: 0
var_dump($s->e); //output: 123
$s->a = 3; //output: This is set function
$s->c = 3; //no output
$s->f = 3; //output: This is set function
?>
结果分析:
如果没有__get方法,执行 var_dump($s->a) var_dump($s->b) 会有致命的错误
如果没有__get方法,执行 var_dump($s->e) 会有一个notice,提示没有定义属性 $e
总结:
1. 从一个难以访问的属性读取数据的时候 __get() 方法被调用
2. 向一个难以访问的属性赋值的时候 __set() 方法被调用
3. 难以访问包括:(1)私有属性,(2)没有初始化的属性
4. __isset() __unset() 也类似

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