回调函数

name=$name;
        $this->price=$price;
    }

}

class ProcessSale{
    private $callbacks;

    public function registerCallback($callback){
        if(!is_callable($callback)){
            throw  new Exception("callback not callable");
        }
        $this->callbacks[]=$callback;
    }


    public function sale(Product $product){
        print"{$product->name}:processing \n";
        foreach($this->callbacks as $callback){
            call_user_func($callback,$product);
        }
    }
}

//$product=new Product('phone',100);

$logger=function ($product){
    print"$product->name";
};

$processor=new ProcessSale();
$processor->registerCallback($logger);

$processor->sale(new Product('shoes',6));
print"
";

$processor->sale(new Product('coffee',8));



class Mailer{
    function doMail($product){
        print $product->name;
    }
}


$processor2=new ProcessSale();
$processor2->registerCallback(array(new Mailer,'doMail'));
$processor2->sale( new Product("phone",1000));