在MVC php程序中$ view是否正确使用全局变量？

Question

I understand that global variables should be avoided generally. As a beginner, I'm trying to understand whether making a $view variable global in a dynamic web program built following MVC principles is one of those cases where globals are a good idea.

In my program, I create the $view (as an object that contains an empty array) in index.php, and turn it into a global in the controllers that use it.

Thanks!

JDelage

Answer 1

In my program, I create the $view as an empty array() in index.php, and turn it into a global in the controllers that use it.

Why? If you controller needs the $view then just pass it in via the constructor or a setter. Dependencies on Globals can always be resolved by using Dependency Injection.

// index.php
$view = array();
$controller = new Controller($view);
$controller->doAction();

Also, please reconsider if the View should be just an array. The View has to be rendered at some point. Rendering is a responsibility I'd see on the View. An array cannot render itself, so I assume you are doing it elsewhere. That would be a violation of the Single Responsibility Principle. I'd rather do something along the lines of (simplified):

// index.php
$view = new View;
$controller = new Controller($view);
$controller->doAction();

// controller.php
...
public function doAction()
{
    ...
    $this->view->setTemplate('/path/to/template');
    $this->view->setVar('foo', 'bar');
    $this->view->render();
}
...