class car  {
    public   $name;
    function   __construct()   {
    }

    public function   showname()   {
        echo   'name   is   '.$this-> name;
    }
    public function setname($name){
        $this->name=$name;
        if ($this->name=='end'){
            exit();
        }
    }

}

$aaa=new car();
$aaa->setname('test1');
$aaa-> showname();


$bbb=new  car();
$bbb->setname('end');
$bbb-> showname();

------解决方案--------------------
想了一下 你是要停止 而不是终止整个运行
PHP code


class car  {
    public   $name;
    protected $goon;
    function   __construct()   {
        $this->goon=true;
    }

    public function   showname()   {
        if ($this->goon==true){
            echo   'name   is   '.$this-> name;
        }
    }
    public function setname($name){
        $this->name=$name;
        if ($this->name=='end'){
            $this->goon=false;
        }
    }

}

$aaa=new car();
$aaa->setname('test1');
$aaa-> showname();


$bbb=new  car();
$bbb->setname('end');
$bbb-> showname();

$bbb=new  car();
$bbb->setname('ttt');
$bbb-> showname();