Using interfaces for TakeDamage

In a previous article ( Use abstract class or interface ) I wrote about interfaces, but I think the example was not clear enough.

First, we need to think about how many game objects in our game will receive damage. Let’s say 3 objects

Made with Miro. Thanks Claudio Grassi

Now, when the Laser executes OnTriggerEnter, will apply damage to the other game object. The code will look some like this:

You got to check the tag in other and also if the other class ( Box Ball Kite ) is not null

Here we have some points to take on account:

• If you change the name of any class, you will need to refactor it, and it’s not just about ‘rename’ it.
• The code works fine for 1, 2 or 3 game objects, but in video games the reality is we can find hundreds of game objects that can execute TakeDamage, so the developer would be forced to write hundreds of else if statements

Here is where we apply the Interface pattern

Interface pattern:

• When a class inherits an interface, the class must implement all of the interface’s methods. That is called ‘contract’
• Each class is free to implement the interface’s methods as desired

Let’s declare the interface

Let’s implement it in all classes

Now we will see why the interfaces are so important

Code improved. Thanks Michael Davis

With this code snippet, the Laser will apply TakeDamage to the other game object.

Laser doesn’t care about the othertag, or if the class name is Box Ball Kite or any other one, the only thing that matters for Laser is if other inherits from ITakeDamage.

If so, it will execute the method implementation of ITakeDamage in other( in this case it will be Box ), which is private void TakeDamage(int damage)