C#

public class Form1{

   public Form1(){
      ...
      Other other = new Other(this);
   }
   //rest of class definition
}

public class Other{

   private Form1 frm1;

   public Other(Form1 frm){
      frm1 = frm;
   }

   public void WriteText(){
      frm1.textOut.Text = "Howdy!";
   }
   //rest of class definiton
}

EuroCPian Spring 2004 Get Together[^]
"You can have everything in life you want if you will just help enough other people get what they want." --Zig Ziglar

public MySingletonClass
{
    // This is the static member variable that will hold
    // the one and only instance of this class.
    private static MySingletonClass onlyInstance;

    // This is the static constructor
    static MySingletonClass()
    {
        // Do initialisation of static member variables.
        onlyInstance = new MySingletonClass();
    }

    // This is the instance constructor
    public MySingletonClass()
    {
        // Do initialisation of instance member variables
    }

    // Allows access to the only instance of the class
    public MySingletonClass Instance
    {
        get
        {
            return onlyInstance;
        }
    }
}

EuroCPian Spring 2004 Get Together[^]
"You can have everything in life you want if you will just help enough other people get what they want." --Zig Ziglar