PHP 构造函数的重载

class abc
{   
    function   __construct()
    { 
        $num   =func_num_args();   
        switch ($num)
        {   
            case 0:   
                echo "none "; 
                break;   
            case 1:
                echo "one "; 
                break;   
            case 2:     
                echo "two "; 
                break;   
        }   
    } 
}   
new   abc()   ; 
new   abc(1)   ; 
new   abc(1,2);

函数的解析我就不写了，太简单了