1namespace presentation.windows.server.domain.payroll
 2{
 3    public class Units
 4    {
 5        static public readonly Units Empty = new Units();
 6        Units() {}
 7
 8        static public Units New(int units)
 9        {
10            return new Units {units = units};
11        }
12
13        public Money value_at(double price)
14        {
15            return price*units;
16        }
17
18        public Units combined_with(Units other)
19        {
20            return New(units + other.units);
21        }
22
23        public Units reduced_by(Fraction portion)
24        {
25            return New(portion.of(units));
26        }
27
28        int units;
29    }
30}