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.