php面向对象继承的使用

<?php

class Nba
{
    const TITLE = ‘标题‘;
    protected static $basketball =‘篮球的‘;
    protected  $rock =‘火箭队的‘;
    protected function color()
    {
        echo ‘红色‘;
    }
    protected static function user()
    {
        echo ‘莫雷是老大‘;
    }

}

class Yao extends Nba
{
    public function demo()
    { 
        $str = self::TITLE;
        $str .= self::$basketball;
        $str .= $this->color() ;
        $str .= $this->rock;
        $str .= self::user();
        echo $str;
    }
}

$obj = new Yao();
$obj->demo();