using System;

​

public enum UI_State {Planter_Grass, Planter_Tree, No_Players}

public class Program

{   

    public static void Main()

    {

        UI ui = new UI();

        ui.UIChanged += PrintUI;

        ui.uiState = UI_State.No_Players;

    }

    public static void PrintUI(UI_State state)

    {

        Console.Write(state);

    }

}

​

public class UI

{

    public delegate void UIHandler(UI_State state);

    public event UIHandler UIChanged;

    public UI_State uiState

    {

        get

        {

            return uiState; 

        }

        set

        {

            uiState = value;

            OnUIChange();

        }

    }

    public UI()

    {

        uiState = UI_State.No_Players;

    }

    public void OnUIChange()

    {

        if(UIChanged != null)

        {

            UIChanged(uiState);

        }

    }

}