public CalculatorForm()
{
InitializeComponent();
calculation = new Calculation();
/* Set up this form to be notified whenever the calculation is updated/changed. The
* reason for using the observer pattern here is to avoid duplicated code updating the
* screen in each button clicked method. */
calculation.AddChangeObserver(this);
/* Set up this form to be notified whenever an arithmetic exception occurs. See
* IArithmeticExceptionObserver for the kinds of exceptions that can occurr and when
* they occurr. */
calculation.AddArithmeticExceptionObserver(this);
}