OpenCart中令人困惑的类和方法调用 [英] Confusing class and method call in OpenCart

问题描述

我有一个框架(OpenCart)Controller类(例如:catalog/controller/product/product.php)，代码如下:

I have a framework (OpenCart) Controller class (like: catalog/controller/product/product.php) the code looks like:

class ControllerProductProduct extends Controller {
    public function index() {
      //some code
      $this->response->setOutput($this->render());
      //some more code
    }
}

有一个类似$this->response->setOutput($this->render());的表达式.我知道该表达式的用途，但是我对它的工作方式感到困惑.

there is an expression like $this->response->setOutput($this->render());. I know what this expression is used for, but I am pretty confused in how it works.

$this引用当前类，即ControllerProductProduct，这意味着$this->response对象必须存在于ControllerProductProduct或其父类Controller中.但这种情况并非如此.该对象实际上以Controller::registry->data['response']->setOutput()的形式存在于父类Controller的受保护属性中.所以不应该这样说:

$this refers to current class i.e. ControllerProductProduct, it means $this->response object must exist in either ControllerProductProduct or its parent class Controller. But this is not the case. This object actually exists in a protected property of parent class Controller as Controller::registry->data['response']->setOutput(). So shouldn't it say like:

$this->registry->data['response']->setOutput();

而不是 $ this-> response-> setOutput();

instead of $this->response->setOutput();

我也提供了Controller类的摘要，以便您有主意.

I am also giving a snippet of Controller class so you can have idea.

abstract class Controller {
    protected $registry;    
    //Other Properties
    public function __construct($registry) {
        $this->registry = $registry;
    }
    public function __get($key) {
        //get() returns registry->data[$key];
        return $this->registry->get($key);
    }
    public function __set($key, $value) {
        $this->registry->set($key, $value);
    }
    //Other methods
}

我不知道这个表达式是如何工作的?知道这怎么可能吗?

I've no clue how this expression is working? Any idea how this is possible?

谢谢.

推荐答案

使用魔术方法 __get()和__set()，这很容易实现.

This is working very easily using magic methods __get() and __set().

如果您试图获取无法访问的类变量(例如，未声明的类变量)，则会调用魔术__get('property_name')方法.

If You are trying to get an inaccessible class variable (e.g. that is not declared) a magic __get('property_name') method is invoked.

因此，当您尝试检索$response时，将调用魔术方法__get()并返回$this->registry->get('response')(因为没有声明$response属性).

Thus when You are trying to retrieve $response, a magic method __get() is called and $this->registry->get('response') is returned instead (as there is no $response property declared).

是的，您可以改写$this->registry->get('response')->setOutput($this->render());，但这没有多大用处，需要更多的写作.让PHP使用__get()方法检索变量是可以的，尽管它不是很干净.

Yes, You could write $this->registry->get('response')->setOutput($this->render()); instead, but this would be of not much use and more writing. It is OK to let the PHP retrieve the variable using it's __get() method, though it is not so clean.

无论如何，解决方案没有任何问题.

Anyway, there is nothing wrong with the solution.

稍微干净一点的解决方案是这样的:

a little bit cleaner solution would be this:

class Controller {
    //...
    function getResponse() {
        return $this->registry->get('response');
    }
    //...
}

然后您可以在代码中调用一个具体方法，这将很清楚:

Then You could call a concrete method in Your code and it would be clear enough:

class ControllerProductProduct extends Controller {
    public function index()
        //...
        $this->getResponse()->setOutput($this->render());
    }
}

但是这意味着每个可能的属性都需要getXYZ方法，而__get()允许您扩展$registry而不需要进一步的工作(在我描述的情况下，如果您要添加另一个属性添加到$register中，您将不得不添加另一个getProperty()方法-但这仍将是更清晰/更干净的解决方案).

But this would mean that there would be a need of getXYZ method for each possible property while __get() allows You to extend the $registry with no further work needed (in the case I described if You would add another property to $register You would have to add another getProperty() method - but still this would be more clear/clean solution).

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