FitNesse will handle any type that implements a static Parse(string) method and overrides ToString().

Parse(string) should construct and return an instance of the Type. The trick is that the ToString() method must produce the same string that was used to create the instance.

string str = "some meaningful string representation of a domain object";
DomainObject instance = DomainObject.Parse(str);
Assert.AreEqual(str, instance.ToString());

---

person fixture	three amigos
field	field?	property	property?	set	get?
Grady Booch	Grady Booch	Ivar Jacobson	Ivar Jacobson	Jim Rumbaugh	Jim Rumbaugh

public class Person
{
	private string firstName;
	private string lastName;

	public static Person Parse(string name)
	{
		string[] names = name.Split(' ');
		return new Person(names[0], names[1]);
	}

	public Person(string firstName, string lastName)
	{
		this.firstName = firstName;
		this.lastName = lastName;
	}

	public override string ToString()
	{
		StringBuilder builder = new StringBuilder(firstName);
		if (builder.Length > 0 && lastName != null && lastName.Length > 0)
		{
			builder.Append(" ");
		}
		return builder.Append(lastName).ToString();
	}
}

public class PersonFixture : ColumnFixture
{
	public Person Field;
	private Person propertyValue;
	private Person methodValue;

	public Person Property
	{
		set { propertyValue = value; }
		get { return propertyValue; }
	}

	public void Set(Person value)
	{
		methodValue = value;
	}

	public Person Get()
	{
		return methodValue;
	}

}