多态

<?php
class light{
    public function ons($g){
        $g->display();
    }
}

class glass{
    public function display(){
    
    }
}

class redclass extends glass{
    public function display(){
        echo '红光';
    }
}
//造手电筒
$light = new light();
//造红玻璃
$red=new redclass();
$light->ons($red);
?>