How to have multiple view classes inheriting from a base view class in touchgfx

[AndrewM]

Hi,

I would like to implement one of the things mentioned in the TouchGFX article 'The Screen Concept and Model-View-Presenter', 

https://touchgfx.zendesk.com/hc/en-us/articles/205717801-The-Screen-Concept-and-Model-View-Presenter

namely:

 If for instance all your screens need to display a status bar at the top, showing current time, battery level, et cetera you can create a base view class containing the status bar only and have all your views deriving from this class, so you get the status bar functionality automatically.

I understand object oriented programming but I'm confused as to how this would work in practice with touchgfx. For each screen, the designer generates (amongst other things):

- a view class templated on a generated presenter class

- a base view class

- a derived view class

so my hierarchy looks like this:

View<StatusBarPresenter>

            ^-- StatusBarViewBase

                      ^-- StatusBarView

View<MainPresenter>

         ^-- MainViewBase

                 ^-- MainView

ie two distinct inheritance hierarchies.

Is the advice above suggesting that I change my MainView to instead inherit from *both* MainViewBase *and* StatusBarViewBase?

When I try this I (understandably) get compilation errors due to multiple inheritance of (non-abstract) classes containing identically named members, in this case eg 

 error: ‘touchgfx::Screen’ is an ambiguous base of ‘MainView’

So I assume the above multiple inheritance is not what is intended.

If not this, then what?

[AndrewM]

As has been mentioned elsewhere, the solution to this problem seems to be composition rather than inheritance. I used a custom container for the status bar menu and just made sure it is used within each screen, which achieves the desired effect.

I would suggest though, that the documentation page I mentioned is updated/corrected in this regard.