Updating the player and enemy to use health

Not only Player and enemy objects but any object can be set up to use HealthSystem. It’s barely an inconvenience; in fact, the object simply needs to implement the IHaveHealth interface.

Assigning the object with health – IHaveHealth interface

Back in the health system UML diagram (Figure 8.1), we see at the bottom that the object having health will implement the IHaveHealth interface (again, some meaningful naming here). Create a new file named IHaveHealth in the Assets/Scripts/Interfaces folder:

internal interface IHaveHealth
{
    void HealthChanged(int amount);
    void Died();
}

We don’t yet have a class for the Player object, only PlayerController. We don’t want to add health to something named controller because it wouldn’t make sense considering the single-responsibility principle – and the controller’s only concern is movement. Let...