php_demo/07面向对象/05重载/__get.php

<?php
    class clsA{
        public $a = 'hello';
        private $b;
        public function __get($name)
        {
            echo "获取{$name}失败，{$name}未定义".'<br>';
        }
    }

    $obj = new clsA();
    $obj -> a = 'world';
    echo $obj -> b; //b未定义，当b被调用时，自动调用了__get，自动传入key
?>