How to extend a function of a separate script?

Unity Engine
1

I’m not sure how to do this, but I have two scripts, [Script A] and [Script B]. Script B is dependent on Script A to function but not vice versa as Script B simply adds more functionality to the object.
If Script A has a public function that is called within Script A, how can I use Script B to basically receive calls from Script A’s function call, so that Script B can make further changes to the object when the function from Script A is called?
By the way, to reiterate, Script A is NOT dependent on Script B to function and I have to keep it that way so I cannot call a separate function in Script B from Script A…
I’d just like to know if it’s possible, and if so how I would execute this.

2

One way to achieve that is via events. ScriptA implements an event and invokes it when necessary, ScriptB adds a listener to the event.

public class ScriptA : MonoBehaviour
{
    public event Action SomethingHappened = delegate {};

    public void DoSomething()
    {
        // do stuff
     
        SomethingHappened();
    }
}

public class ScriptB : MonoBehaviour
{
    void Awake()
    {
        base.GetComponent<ScriptA>().SomethingHappened += onSomethingHappened;
    }

    private void onSomethingHappened()
    {
        // do more
    }
}

Note: There are more ways to implement events (just google e.g. “unity c# events”), this is just one of them. If you want to assign the listeners in the editor, you should check UnityEvents.

1 Like
3

Another option is inheritance, depending on the specific implementation:

public class ScriptA : MonoBehaviour
{
    protected virtual void DoSomething()
    {
        // Does something
        ...
    }
}

public class ScriptB : ScriptA
{
    public override void DoSomething()
    {
        base.DoSomething();
       
        // Does something more.
        ...
    }
   
    public void DoSomethingElse()
    {
        base.DoSomething();
   
        // Does something else
        ....
    }
}
1 Like
4

Thanks, answers were very insightful, I think Events would be better suited to my needs :slight_smile: