Derived class linker - is this wrong?

Question

We have this situation:

                    Window  Keyboard
                    ^         ^
                    |        /
                    ApplicationWindow 

so

class Window { }
class Keyboard { }
class AppWindow : public Window, public Keyboard { }

Now, Keyboard wants to access a property in ApplicationWindow, for example, it wants to call the ApplicationWindow's getWidth() property.

The solution I have is to place a pointer to an ApplicationWindow inside Keyboard.

I'm trying to use multiple inheritance here as composition, while I know actual composition is more strongly encouraged, I wanted to try MI.

In any case I'd need a back link to the ApplicationWindow instance from Keyboard if I used composition anyway..

Answer 1

I would say it would be a lot cleaner to move the property into the base class Keyboard.

ApplicationWindow would have access to it as well since ApplicationWindow extends Keyboard.

You don't want the base class to need to have any knowledge of any sub classes.