How to make an update interface which gets called in main update

Question

Interface:

public interface IonStateLoadUpdate
{
    void onStateLoadUpdate();
}

Class 1:

class foo
{
    private void onLoadUpdate()
    {
       // How to call interface onStateLoadUpdate here ?
    }
}

Class 2 which inherits IonStateLoadUpdate

class poo: IonStateLoadUpdate
{
     public void onStateLoadUpdate()
     {
         // This should get call once foo calls onLoadUpdate
     }
}

Answer 1

What about this:

class foo
{
    private void onLoadUpdate(IonStateLoadUpdate x)
    {
       IonStateLoadUpdate.onStateLoadUpdate();
    }
}

Then:

var p = new poo();
...
...
var f = new foo();
f.onLoadUpdate(p);