Imitating Multiple Inheritance in PHP

Question

I am working on my own MVC framework and found myself stuck. I need the following construction:

 Controller  
      --> Backend_Controller
           --> Backend_Crud_Controller
       --> Frontend_Controller
           --> Frontend_Crud_Controller

Both 'Backend_Crud_Controller' and 'Frontend_Crud_Controller' have the same functionality and thus they should extend another class named 'Base_Crud_Controller', the only difference comes from the 'Backend/Frontend' Controllers which implement different mechanisms.

Basically they should inherit both classes but my problem is that 'Backend/Frontend' controller doesn't necessarily extend 'Base_Crud_Controller'.

I know multiple inheritance doesn't exist in PHP but I am looking for a solution, I choose to refrain Mixins (like in Symfony) as I don't consider that an elegant solution.

Interfaces do not suit me as all of these end up as concrete classes that should implement methods.

Could you please tell us what each of this classes do? Why did you decide to create such inheritance mode? I've got bad feelings about what you're trying to do. — Crozin
The 'Controller' represents basic controller functionality as in the MVC world. Backend/Frontend controller both extend 'Controller' and implement different logic. In both the Frontend/Backend controllers I could have CRUD_Controllers which implement basic CRUD functionality but note that not all Frontend/Backend controllers need to implement CRUD. — fabieno

Gordon Gordon · Accepted Answer · 2010-05-03T11:53:44

Consider using Decorators or rethinking your design.

class FrontEnd
{
    protected $baseController;
    public function __construct(BaseController $controller) { /* ... */}
    // ... 
    // methods specific to Frontend
    // ...
    public function __call($method, args) {
        // implement __call to delegate other methods to BaseController
    }
}

You can also create a BackEnd, and Crud Decorator and stack these together, e.g.

$crudBackEndController = new Crud(new BackEnd(new BaseController));

Imitating Multiple Inheritance in PHP

1 Answers