ExplicitOperator.cs

using System;

namespace ExpressionTest
{
	public class ExternalPerson
	{
		public int Id { get; set; }

		public string FirstName {			
			get;
			set;
		}

		public string LastName {
			get;
			set;
		}

		public ExternalPerson ()
		{
		}
	}

	public class Person
	{
		public long Number { get; set; }

		public string FullName {
			get;
			set;
		}

		public static explicit operator Person(ExternalPerson externalEntity)
		{
			return new Person()
			{
				Number = externalEntity.Id,
				FullName = externalEntity.FirstName + " " + externalEntity.LastName
			};
		}

		public Person ()
		{
		}
	}

	public static class Test
	{
		public static void ExplicitOperator()
		{
			ExternalPerson externalPerson = new ExternalPerson () {
				Id = 1100058,
				FirstName = "Bob",
				LastName =  "Andrews"
			};

			Console.WriteLine (externalPerson.Id);
			Console.WriteLine (externalPerson.FirstName);
			Console.WriteLine (externalPerson.LastName);

			Person simplePerson = (Person)externalPerson;

			Console.WriteLine (simplePerson.Number);
			Console.WriteLine (simplePerson.FullName);

			Console.WriteLine ("Press enter to exit.");
			Console.ReadKey ();
		}
	}
}