Whip Monstrous Code Into Shape - 04 God Object Cleanup #1: Pass-Through

Any developer who has worked on the same project for a year or more will be well aware of the fact that, if you're not careful, your User class can quickly turn into a monstrous God object. In the next few videos, one tip at a time, we'll review techniques you might implement to clean things up.

In this first example, we'll recognize related methods, and extract them to a dedicated object - which we then pass through to from our main User class.

之前三个视频讲的都是如何更好的维护控制器的简洁有序，接下来这3个视频主要讲的是如何清理模型，标题我也不知道怎么翻译好，大家理解就行。

随着时间的过去，项目体积也不停的递增，相应的你的模型也越来越臃肿，首当其冲的就是 User 模型了。打个比方，一个简单的博客系统，就像 laravel-china 一样吧，一个用户有话题、评论数和话题，通常我们会写在模型中（不过laravel-china好像会更新到数据库中？打个比方..）：

public function commentsCount()
{
    return $this->comments->count();
}

public function topicsCount()
{
    return $this->topics->count();
}

public function favoritesCount()
{
    return $this->favorites->count();
}

然后可以很简单的通过 $user->favoritesCount() 的方式访问。

视频中给出了一个方法，因为这三个属性都是代表用户的一个状态，所以可以通过添加一个 state 类来把这三个状态封装起来。用户模型添加一个 state 方法：

public function state()
{
    return new UserState($this);
}

然后把这三个方法移到 UserState 类中：

class UserState
{
    /**
     * @var User
     */
    private $user;

    /**
     * UserState constructor.
     * @param User $this
     */
    public function __construct(User $user)
    {
        $this->user = $user;
    }

    public function comments()
    {
        return $this->user->comments->count();
    }

    public function topics()
    {
        return $this->user->topics->count();
    }

    public function favorites()
    {
        return $this->user->favorites->count();
    }
}

然后就是通过 $user->state()->favorites() 访问了。你也可以加个 __get 魔术方法，看起来就像是调用属性:$user->state()->favorites。

public function __get($attribute)
{
    if (method_exists($this, $attribute)){
        return $this->{$attribute}();
    }
}