What's the best C# pattern for implementing a hierarchy with an enum?

Question

I\'m implementing value types which represents a distance (or length). There\'s an enum that represents the different units of measure, eg:

public enum Distance         


        

Answer 1

Maybe all you need is a function that returns a corresponding unit subset

class UnitSystem
{
  public enum Type
  {
    Metric,
    Imperial
  }

  public static DistanceUnit[] GetUnits(Type type)
  {
    switch (type)
    {
      case Type.Metric:
        return new DistanceUnit[] {
          DistanceUnit.Millimeter,
          DistanceUnit.Centimeter,
          DistanceUnit.Meter,
          DistanceUnit.Kilometer
        }

      case Type.Imperial:
        return new DistanceUnit[] {
          DistanceUnit.Inch,
          DistanceUnit.Foot,
          DistanceUnit.Yard,
          DistanceUnit.Mile
        }
    }
  }

  public static Type GetType(DistanceUnit unit)
  {
    switch (unit)
    {
      case DistanceUnit.Millimeter:
      case DistanceUnit.Centimeter:
      case DistanceUnit.Meter:
      case DistanceUnit.Kilometer:
        return Type.Metric;

      case DistanceUnit.Inch:
      case DistanceUnit.Foot:
      case DistanceUnit.Yard:
      case DistanceUnit.Mile:
        return Type.Imperial;
    }
  }
}