我们在编写PHP方法时，通常有若干个参数，就像下面的代码：

Class Book
{
    public function create($name, $cateId, $author)
    {
        $params = [
            'name' => $name,
            'cateId' => $cateId,
            'author' => $author
        ];
    }
}

没有任何问题。

但是，随着业务的发展，参数可能会不断增加。就像上面的例子，创建一本书刚开始只有name/cateId/author三个参数，慢慢可能就变成了下面这样：

Class Book
{
    public function create($name, $cateId, $author, $year, $price, $publish, $country, $language)
    {
        $params = [
            'name' => $name,
            'cateId' => $cateId,
            'author' => $author,
            'year' => $year,
            'price' => $price,
            'publish' => $publish,
            'country' => $country,
            'language' => $language,
        ];
    }
}

It works well！但是看起来总觉得不太优雅，当你调用这个方法的时候，鬼才知道参数的顺序是怎么样的！

如何优化呢？我们可以尝试把参数对象化。请看下面的代码：

class BookModel
{
    protected $name;
    protected $cateId;
    protected $author;
    protected $year;
    protected $price;
    protected $publish;
    protected $country;
    protected $language;

    public function getName()
    {
        return $this->name;
    }

    public function setName($name)
    {
        $this->name = $name;
    }

    public function getCateId()
    {
        return $this->cateId;
    }

    public function setCateId($cateId)
    {
        $this->cateId = $cateId;
    }

    public function getAuthor()
    {
        return $this->author;
    }

    public function setAuthor($author)
    {
        $this->author = $author;
    }

    public function getYear()
    {
        return $this->year;
    }

    public function setYear($year)
    {
        $this->year = $year;
    }

    public function getPrice()
    {
        return $this->price;
    }

    public function setPrice($price)
    {
        $this->price = $price;
    }

    public function getPublish()
    {
        return $this->publish;
    }

    public function setPublish($publish)
    {
        $this->publish = $publish;
    }

    public function getCountry()
    {
        return $this->country;
    }

    public function getLanguage()
    {
        return $this->language;
    }

    public function setLanguage($language)
    {
        $this->language = $language;
    }
}

上面定义了一个BookModel类，包含了一些属性。然后我们对create方法进行改造，要求它的参数为BookModel类。由于BookModel的数据结构是明确的，使用起来非常方便。create方法调整后：

Class Book
{
    public function create(BookModel $bookModel)
    {
        $params = [
            'name' => $bookModel->getName(),
            'cateId' => $bookModel->getCateId(),
            'author' => $bookModel->getAuthor(),
            'year' => $bookModel->getYear(),
            'price' => $bookModel->getPrice(),
            'publish' => $bookModel->getPublish(),
            'country' => $bookModel->getCountry(),
            'language' => $bookModel->getLanguage(),
        ];
    }
}

看，面向对象编程的优势在这里凸显出来了！